Questyle M15 · Mobile Lossless Headphone Amp with DAC

nickdhrubo

New Head-Fier
Questyle M15 - Redefining what dongles can do
Pros: Sound
Low power consumption
Excellent dynamics
Cons: Average single ended output
No DSD Playback capabilities
Prone to RF interference, especially with the stock cable.
You get what you pay for; not with the Questyle M15, you get much more! If you don’t want to read further, let me make it short, you get top class desktop grade audio performance in DAC that fits on the palm of your hand.


The M15 uses Questyle’s patented current amplification technology featuring Class AB amplification. I am not going to pretend to understand all the intricacies of current amplification technology, but I can say that what Questyle did, it works and it works damn good! There is only one thing about the M15 that I don’t like and I am going to get it out of the way in the beginning, that is the absence of volume control buttons or knobs in the unit.

Questyle M15



Physical Attributes & what's in the box:


The M15 looks unique with a glass front letting you see the circuitry inside it. This might be for everyone but I quite like it. I was a bit apprehensive at first about the glass built, but that feeling didn’t last long after using the unit for a while. It does not feel flimsy in any way and I can’t imagine it breaking unless something heavy falls on it. The glass is covered by a thin film of plastic to protect it against scratches. The rest of the body is made of machined aluminum, nothing special there. It has a small switch in its size allowing you to change the gain between high and low. On its front is a USB C port and on the back is a 3.5mm and a 4.4mm port allowing both single ended and balanced connection. The packaging is fairly modest, it just includes a type C to type C and a type C to type A cable.

Questyle M15 + Koss Porta Pro

Specifications:


Output Power: 3.5mm:RL=300Ω,Po=11.97mW

Vout(Max)=1.895Vrms,THD+N=0.00045% 4.4mm:RL=300Ω,Po=22.60mW, Vout(Max)=2.624Vrms,THD+N=0.00057%


Questyle just mentions the power output at 300Ω, so I was a bit confused at first about what to expect but in handled everything that I threw at it with flying colors.They used a ES9271AC DAC capable of handling PCM:PCM: 32kHz – 384kHz (16/24/32Bit) DSD: DSD64(1Bit 2.8MHz) , DSD128(1Bit 5.6MHz), DSD256(1Bit 11.2MHz). The background noise is less than -125dB and I could not hear any noise during my listening. It also acts as a MQA decoder (for those who care).

Questyle M15 + Dunu Zen Pro In ear monitor



Pairings:


I tried the M15 with almost everything I had in my arsenal curious to see how it handled each of them:

  1. Dunu Zen Pro
  2. Sennheiser HD6XX
  3. Audeze LCD-X
  4. Hifiman Arya V3
  5. Koss Porta Pro

The M15 did not fall short with any of them.

Questyle M15

Sound Impressions:


Power:The M15 delivered power to all my headphones and earphones leaving nothing to be desired more from such a portable device. I used the M15 with my google Pixel 6, Shanling M7 DAP and also from my PC. With the portable devices, in high gain, I did not have to increase the volume more than 50% to drive the HD6XX, Arya and LCD-X pretty loudly. The Porta Pro and Zen Pro all played fine at low gain. But when I connected the M15 to my PC, it became a different monster. At 30% volume, it was driving the Arya at ear splitting levels. I had to adjust the volume carefully to find a comfortable listening level. I haven’t seen a lot of entry level desktop amps output this amount of power. That being said, the M15 did pick up some noise when connected to the USB port of my computer, but I guess that is to be expected because we know how noisy those ports can be.


It drove all 3 of my headphones with authority which matched the level of my Burson Audio Soloist 3X. While the Soloist 3X is way more powerful, I really don’t need that amount of power for any of my cans. I haven’t found any dongle yet, bar the M15 which can properly drive the HD6XX.

Questyle M15 + Audeze LCD-X headphone



Tonality:M15’s tonality is neutral but not cold, I enjoyed all of the aforementioned pairings a lot. What surprised me most is that I liked the pairing of the HD6XX of the M15 more than the pairing with the Burson Soloist 3X. The Soloist 3X is a class A amplifier, but compared to the M15, the Soloist and HD6XX pairing is a bit too warm for my taste. It muddies the sound of the 6XX a bit. It’s a well known fact that the Sennheiser HD6 series prefers a warmer source, but not to my ears. The 6XX sounded more organic and natural to me with the M15, spewing out details that I have seen from $500 upward amps. Listening to Jeff Buckley’s “Mojo Pin”, “Last Goodbye” and “Lover, You Should’ve Come Over”.the vocals were full bodied and lush, solidifying the 6XX’s strong suites.Questyle showed with this dongle that the complaints we used to hear about ESS’s “digital sound” is just not true anymore, far from it. It sounds as analog as analog can get.

Questyle M15 + Sennheiser HD6XX Headphone



Technical Performance:The technical performance comes very close to the Soloist 3X paired with the Topping D90SE DAC, which totals at $2000 retail. The M15 is a detail monster with a very natural presentation. The D90SE using the top of the line ESS 9038 Pro DAC provides ample details needless to say. But the way M15 does it is more natural and does not seem “in your face”. It drove the LCD-X and the Arya with speed and prowess that I did not feel the need to resort back to my desktop amp. The attack and decay of both the planars were blazing fast. I used the track “Festival in Bagdad - The Sea - The ship Goes to Pieces on a Rock” by Chicago Symphony Orchestra and Fritz Reiner to test the speed, separation and how it handles complex passages, also “Pace” by Nubya Garcia. The separation between the notes were excellent and distinguishable. The dynamics and resolution it provides is excellent, more understandable with well recorded tracks from any genre. I was able to hear the faintest sound of brush drumsticks on the far right in a track, the brush dragged along the drum. While I found the imaging to be fine, my only gripe is that the soundstage could be a bit wider, but I am really nitpicking here. I am comparing the soundstage with the other attributes of the dongle.


Bass:The bass response from the M15 is clean, precise, fast and powerful. With the LCD-X and the Arya they slam hard. Listening to the “Burning down the house” by Talking Heads, the bass was textured and layered. I used “Angel” by Massive Attack to test the sub-bass. It reached pretty low and with prowess. With the Zen Pro too, the bass is rumbling.


Mids:The mids is one of the strongest traits of the M15. Both male and female vocals sounded full and lush. It wasn’t pushed forward in any way, neither was it recessed. It was textured, nuanced and I got the feeling that I was listening to the vocals just as the mixing and mastering engineers intended. The mids are almost … addictive.


Treble:To test the treble, I played “Batonga” by Santana. If a headphone is sibilant, I can usually tell from the female vocals of this track. None of my headphones sounded sibilant in any way, it was airy and natural and energetic. Treble lovers like myself will quite enjoy the M15. This is unlike how a lot of Chinese manufacturers reproduce the treble from their dongles.


All throughout the frequency range, the music flows like water. No frequency is over accentuated, none is recessed.

Questyle M15 + Hifiman Arya Headphone



Conclusion:


Who is this dongle for and who should buy it? This dongle is for anyone who prefers a clean, neutral and engaging sound. It's for anyone who does critical listening without losing the enjoyment factor. It is for headphone users like me who prefer headphones over earphones, it can most probably replace your desktop setup and you will be happy that it did. It can mop with probably any dongle that’s out there and a lot of desktop DAC AMPs. The M15 might be the only source that you might need for a very long time.

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rev92

Reviewer at Ear Fidelity
Questyle M15
Pros: Lots of usable power
Dynamic, fun sound
Absolutely spectacular bass
Draws very little power from your source
Great build quality
Window, showing the internals
Cons: Lack of internal volume control
Can pick up RF interference
Treble can feel a little hard

Introduction to the Questyle M15 review​

Questyle is a Chinese company that has been on the market for quite some time now. Unlike their other counterparts at the time, they always aimed at the premium market. Quality and performance, over low prices. One of the first purely Chinese companies that actually threw a challenge in the face of more established companies on the market. That is something to admire, as it was in complete opposition to what their competition was doing. There also is a more personal story that I have with Questyle.
I can remember the company appearing on the Polish market as I was learning the ropes of audio reviewing. I even listened to the CMA600i, I believe, but left the website before I got it in for a review. Guess, who later did that review. The one and only, Paweł from Ear-Fidelity. What makes it even funnier is that we actually didn’t know each other yet. He was my replacement when I left. Who’s that guy, with that ridiculous hairstyle? Somebody mentioned he looks like a pineapple. It lives rent-free in my head now.
Well, now we are good friends and today he’ll be at my 30th b-day party. Maybe I’ll buy him a pina colada… Small world, huh? It’s worth noting that the review was very favorable, and he even said it was one of the best devices available at the time. I’m not translating that directly from Polish, so let’s say you trust me on this one.
Questyle saw the rise of portable audio and the need for the best possible sound quality outside the home. That inspired them to create the subject of this review. The M15 is a portable Hi-Res DAC/AMP, a so-called dongle. It connects to your phone via a USB type C cable and allows you to utilize your IEMs and headphones on the go. Its goal is to combine Hi-Res audio, capable amplification, and premium build quality. Did they succeed? This review of Questyle M15 will tell you everything.

Packaging​

Box of reviewed Questyle M15

I’m fresh after doing the Andromeda Emerald Sea video (check it out on YouTube!), with its absolutely crazy packaging. Well, here we have the absolute opposite.
We only get the most basic box, holding essentials. In the box you’ll find: the dongle and the USB type C pigtail cable. Done. Whoa, reviewing the Questyle M15 is so easy.
The leather case is available separately for $25 in a couple of colors: black, red, ivory, green, brown and grey. I got the black one because it was the only one that I could grab locally, but bet your ass, that Ivory would look absolutely stunning.

Design and Build Quality​

Reviewed Questyle M15 with Hifiman Svanar


I have to say, that the reviewed M15 lives up to the “Questyle hype” from my memories. Seems that the company hasn’t strayed from those “ancient” times. The body is made out of milled aluminium and the top is made out of either acrylic or glass. It’s like a back window in a Lamborghini. It’s not for you to safely park backwards. It’s so you can see the engine! In this case, the electronics are on the display. Why can’t girls get me that aroused? Laser-engraved markings and text cover the whole device. You can see that it is not a cheap toy. Fitting is impeccable.
The user experience was really good, especially after I bought the leather case, and stopped worrying about scratching it so much. Still managed to get a tiny scratch on the glass, curious if you can spot it in the pictures.
The dongle has one neat function: when nothing is connected to the output, it turns off to conserve energy. My main issue with the reviewed Questyle M15 is the fact that it doesn’t have integrated volume control. You control the volume from your source. My Samsung S21 FE 5G has a ridiculously large step (something around 10%) which can’t be changed in the settings. I had to find a program called Sound Assistant that allowed me to change that and reduce the volume control steps. Besides that, using the Questyle M15 is great.

Tech inside the reviewed Questyle M15​

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The Questyle M15 features a couple of interesting solutions, which I’m more than happy to nerd out about.
Let’s start with the star of the show, the ESS Sabre ES9281AC codec. It’s an impressive IC, integrating a USB Audio interface, very good DAC, ADC, and some other features like output jack detection. How they managed to fit all that in such a small package is beyond me. It supports PCM 32bit/384kHz and DSD256.
On top of that, Questyle’s engineers implemented their flagship technology, the CMA (Current Mode Amplification) SiP headphone amplifiers. Four of them to be exact. Current mode amplification is not as popular as voltage mode amplification, but some manufacturers swear by it, including Accuphase. Current mode amplifiers are the most known for their speed, they can handle some very high-frequency signals.
The SiP has a bandwidth of 1 MHz with only 0,0003% distortion. Those are some nice numbers. What about the power? You won’t catch the reviewed Questyle M15 slacking. The official data shows 22,6mW @ 300 Ohm with no rating for the 32 Ohm load. Output voltages are rated at 3,5mm: 1,9V and 4,4mm: 2,6V. I know it’s hard to compare those numbers with other dongles. In my experience, the reviewed Questyle M15 is more powerful than I would ever need it to be, driving Meze 99 Classic and low-sensitivity IEMs with ease.
For our convenience, we can select gain, either low or high. I would prefer the low gain to be actually lower than it is. I still don’t have as much volume control over the Andromeda ES as I would like to. Also, the high gain is very high and even the headphones I tried didn’t need that much. The power supply used is named Torex and is focused on keeping the efficiency as high as possible.
I have to admit, that while on low gain the reviewed Questyle M15 uses minuscule amounts of energy. My phone is very happy about that. Not having to load your phone after a ride across the city is a nice feature. One last thing. The M15 has a rare tendency to pick up some interference while not playing. Like once a day. This doesn’t happen at all when listening to music, but c’mon Questyle.

Sound​

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Most of my testing was based on Campfire Audio Andromeda Emerald Sea and Unique Melody MEST. I have used Time Stream cable for the Andromeda and Erua Audio Tawa for the MEST. I tested driving capability on Meze 99 Classic (no issues) and HiFiMan Sundara Classic (didn’t work that well). Other IEMs used in testing: Letshuoer EJ07M, Craft Ears Aurum. Dongles used for comparison are listed later on. As usual, I’m using 4,4mm connections wherever possible.
Well to start off, no surprises here really. First of all, the sound quality is really high. Questyle is one of the brands I would consider a safe choice quality-wise. Secondly, it sounds like it has a Sabre chip. Incredible dynamics, powerful bass, good sound staging, clear-cut sound, and black, velvety background. It sounds like some of my other reviews, but it’s not my fault that ESS Sabre dominates the market. I’m aware of that, but not much I could do about it.
Okay, I have something new for you! The newest generation of Sabre DACs is not as fatiguing to me as the previous ones and that applies to the one used in the reviewed Questyle M15. They had to change something in the design. The tonal balance of the M15 is a bit boosted in the top and bottom ends. It builds extra excitement and increases the foot-tapping factor, but it may not be the best thing for studio usage. Let’s dive into more details.

Bass
The first thing I have noticed with the Andromeda is how well the Questyle M15 drives them. Zero noise, maximum dynamics. I was dumbfounded at what bass the ES started producing. Big, bold, with the punch of a martial artist. It is more snappy like a lightweight MMA, than a heavyweight boxer, but still.
Listen to Kanye West’s Black Skinhead, this song really benefits from the reviewed Questyle M15’s sound character. In the beginning, you get a heavy drum bass with some quick jumps left and right on the soundstage. Controlled aggression, lightning-fast transitions, and complete silence in between the sounds really took me off guard. It’s absolutely amazing how the Andromeda ES transformed under the M15’s iron grip. On the other hand, a bass line from Starlight, by Muse has incredible complexity to it.
It goes throughout the song, and you can try it as a reference for textures. It’s a big sound with lots of detail with drums on top of it all. It’s a great test for equipment and you can see how much control the Questyle M15 has when drums come in after the intro and the bass line doesn’t lose anything. I’m thoroughly impressed by the performance of the Questyle’s dongle.

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Midrange
The midrange is slightly recessed in comparison to other ranges, but it doesn’t lose its qualities. Great things are expected from dongles at this price point. Reviewed Questyle M15 delivers. One of my favorite pop artists Dua Lipa has this incredible show at Tiny Desk. Tiny Desk is an acoustic, live music show on YouTube. You can find big names mixed with a lot of indie artists from different genres. Dua Lipa might have one of the best ones.
Her sexy, pleasant voice is supported by a choir, a guitar, and a bass guitar. Add some simple samples and you’ll be blown away. My favorite song from the show is Pretty Please. Just layers of voices, after around 40 seconds the choir starts to take a greater part and with the mix of Andromeda ES and Questyle M15, you can listen to each voice individually. It made me happy to be able to enjoy one of my favorite shows to this degree. Are you craving something more fancy? How about an indie artist named Kevin Morby? On his album Sundowner, you can find this song called Brother, Sister.
Wait till the first chorus, where he uses vocalization followed by an acoustic guitar. The amount of insight into the sound that you are getting is really good. It is crazy how such a simple composition can speak to your emotions. Courtesy of the Questyle M15.

Treble
When it comes to treble, the M15 pushes them a bit harder, which is compensated by the Andromeda ES softness at the top. For this part, I relied more on the UM MEST. The treble of the Questyle M15 is big, and controlled.
The intro to the Sanitarium by Metallica features guitars supported by cymbals. Especially the first one sounds with a suitable impact. Emphasis on treble helps here to add extra energy and freshness to a pretty complex composition by one of my favorite bands. I do feel like the treble on the reviewed Questyle M15 tends to be a bit metallic, even when it comes to sounds that shouldn’t sound like that. Clandestina (Cocaine remix) by Filv, Edmofo, and Emma Peters is the song you know, but couldn’t remember what it’s called.
No thanks are necessary. Here the M15 presented a controlled and clear-cut sound, that sometimes felt a bit too hard. It is still a really good performance, but later on, you’ll learn about competition that does it better.

Soundstage
One of the biggest tests for sound staging was Dua Lipa’s show at Tiny Desk. I’m surprised by how well are those shows recorded. Reviewed Questyle M15 allowed me to easily place all of the musicians and singers in front of me.
Each of them was a separate sound source with no mixing between them. They were very close to me, as both Questyle M15 and Andromeda ES tend to have a closed-in presentation. For sound staging reasons I preferred the MEST with its tendency to explode the sound and push sources away from the listener.
The Questyle M15 does a good job at soundstage width and depth, but the competition is one step ahead. Really good performance on the part of M15.

Comparisons​

Cayin RU6, NOS – $249
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The RU6 by Cayin is one of the first dongles (if not the first one) to feature an R2R DAC. It promises and delivers a completely different sound signature than Delta Sigma DACs. It pushes the midrange into the first line. The treble and bass are pushed to the side a fair bit. The soundstage is much more open than on the Questyle M15. Refer to the Dua Lipa Pretty Please as a reference track. Pretty please.
Same thing on Clandestina (Cocaine remix), everything is much more open with more air between the instruments. In terms of bass, it is the weakest in the amount and the quality. Whether it’s Kanye West Black skinhead’s intro that lacks the bang, or Muse’s Starlight, with its famous bassline lacking the detail. It’s the bottom of the comparison here. Midrange, on the other hand, takes the cake, and with the Andromeda ES… It’s a crazy experience. I could have RU6 only to listen to the midrange. Kevin Morby’s Brother, Sister is magical. Natural, bold, thrilling voice and guitar. Absolutely top-tier performance. Neither M15 nor W4 have anything to say here.
With Dua Lipa’s show? Don’t even ask. I’m in love with her, just didn’t inform her yet. Please, call me. Pretty please? The treble on the RU6 is not as pronounced as in other dongles but is very light, sweet, and open. Less aggressive in Sanitarium by Metallica, either in the beginning or close to the end, it holds its own and compensates the amount with quality. Oh btw, don’t use UM MEST with the RU6. It doesn’t sound good. Anti synergy, just like me and pineapple pizza.

L&P W4, TUNE 1, Filter SLOW – $450

The W4 is still pretty fresh, as it had a premiere this year. The top dog from Luxury & Precision uses the LP5108, which is a combo of two DACs from Cirrus with some power regulators in a single module. I think they might oversold it a bit, as people feel deceived by the nature of the module. Still, there are some merits to doing that, namely great power delivery and decoupling.
You might have noticed the price tag. Yes, it’s not a typo. It is crazy expensive for a dongle (besides the ridiculous Gold Bar from iFi Audio). Yet still I can’t deny, that the W4 seems to be the best dongle on the market. In the top 3, no doubt. It takes the pros from both the M15 and RU6 but leaves out the cons. Pretty balanced character (with a small bump in bass), lots of power, and a great sound. It’s gonna be hard to return it to the owner. Thank you Grzesiu for lending it to me. Sound staging of the W4 is precise as with the M15, yet open and spacious as with the RU6. Take Dua Lipa’s Tiny Desk concert and it will be a top-tier performance.
The bass is not as powerful and dynamic as with the M15, but it still is excellent. Power, control, and detail. Doesn’t break a sweat with Kanye, and neither does fine detail with Muse. The midrange is not as good as with the W4, but it is pretty close. Detail, natural timbre, and smoothness can be heard throughout the whole Brother, Sister by Kevin Morby. Treble is another win, being the best out of all tested devices.
Open, airy, and sweet, but with enough authority to balance other ranges. The W4 played well with both the Andromeda ES and the MEST. It is a complete package, but it costs basically the same as the other two dongles combined. So, you know…

Pairing​

I will compare the pairing with the help of Tom Cruise and his two best roles.

Andromeda Emerald Sea

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Andromeda ES with the Questyle M15 is like Tom Cruise in Collateral. Vincent was precise and calculated, yet charming and incredibly dangerous. The darker tuning of the Andromeda means you might want to use the silicone tips to get a more balanced response. The amount of precision this combo gives is incredible. As mentioned in our Andromeda ES review on YouTube, the Questyle M15 became my daily driver.
The bass from this combo will break your stereotypes about BA IEMs. It’s crazy good. The dryer midrange of the ESS Sabre family is greatly supplemented by the IEM’s richness in this regard. It still has plenty of charm. The top end gets dominated by Andromeda ES’ roll-off, so as mentioned before, you either deal with it or use silicone tips. I can live with that, as it is still a very respectable performance. All in all, incredible combo, and I can see myself using it for a long, long time.

UM MEST

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The MEST with the M15 is like the best role of Tom Cruise. As a wise man named Les Grossman from the movie Tropic Thunder once said:
Now I want you to take a step back… AND LITERALLY *** YOUR OWN FACE!
You can’t censor me, it’s a movie quote. This combo is just an obnoxious level of fun. It’s like the titular character, completely over the top. They will take you on a ride with a bass bigger than his bald spot. It will make you break some dance moves like Ludacris’ You don’t know me like that is in the air. But, on a more serious note. It’s a great combo.
The set with Andro is for enjoying music. This one is for enjoying yourself. Huge soundstage, with sound sources all around you, like assistants circling around Les. The Bass is something the MEST is known for with its bone conduction driver and the Questyle M15 takes full advantage of that. Just an ungodly rumble. The SiP amplifier is a very capable one. The midrange is on the back foot here as both devices don’t make it a priority. It’s still solid for the price, but let’s be honest.
You don’t buy the MEST for midrange, don’t you? The treble does an amazing job of countering the bass and making sure it doesn’t steal the show. Bright, bold, open and smug. Cuts through the low-frequency fatness like a pickle cuts the fatness of a pork belly on a sandwich. So to summarize it all, it’s an illegal amount of fun. If you like to always have fun, when listening to music, it might be a combo for you.

Questyle M15 Review – Summary​

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Good to see, that Questyle didn’t lose its direction over the years. Their focus is to make high-quality audio equipment and this review confirms that in my eyes. I have no doubt, that Questyle M15 is one of the best dongles on the market. Premium build quality and a fantastic sound are a testimony of that. While not as feature-packed as its competition, it steals the show with detailed, v-shaped explosive sound and great drive capabilities.
If you like the stereotypical sound of ESS Sabre DACs, you’ll be in heaven. Or maybe you are interested in a stupidly good-sounding dongle, that won’t drain your battery in 3 hours?

It’s not flawless though. The RF interference it can pick up when music is not playing is something that should be addressed. It happens very rarely, but still: shouldn’t. The other feature I dislike is the lack of integrated volume control. I would prefer not to use my smartphone for that since it was a challenge to figure out how to adjust the volume control step.
All in all, M15 still deserves a recommendation. I’m happy to use it as my daily driver, as it replaced my iFi Audio GO Bar. If you are on the lookout for a dongle that will drive anything while sounding mighty, you need to try the Questyle M15.


Highly Recommended.


Big thanks to Questyle for providing the M15 for this review. I wasn’t paid or asked to say anything good or bad about this product, all of the above is just my personal, unbiased opinion.
joydivisionnewdawnfades
joydivisionnewdawnfades
Very good review @rev92.
You can use the dongle with your Samsung S21 FE 5G?
I have the same phone and i can only use the Samsung jack adapter on the USB-C port :cry:

kmmbd

500+ Head-Fier
Dongle Par Excellence
Pros: Unique design that stands out
– Doesn’t get too warm given the power output
– Good support for both Android and iOS
– Class-leading resolution
– Can power almost any IEMs and even some headphones
– No hint of glare when driven from laptop
– Fantastic instrument separation
Cons: Drains the host’s battery when in high gain
– Somewhat narrow staging
– Unforgiving nature might not suit the bright or peaky IEMs
– Slight upper-midrange glare when driven from phones
– No volume or playback controls
– Prone to RF interference
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Had I been a YouTube reviewer, I would have littered a ton of “fire” emojis across this review title. The thumbnail would allude to something akin to “shut-up and buy it”, while a somewhat disturbing image of my agape face would round-up the level of bewilderment and bemusement that the M15 has evoked.

Sadly, in the written form, I am but slave to the words.

Questyle M15 is the flagship dongle in the brand’s lineup, and overall, perhaps the best dongle one can buy. Sadly, such sweeping generalizations do not favor anyone, and everything is reliant upon context.

So, this review is to contextualize the reasons why the Questyle M15 might be the best dongle ever, or why it may not be the right dongle for certain use-cases. Read on.

Note: the ratings given will be subjective to the price tier. Thanks to Questyle for sending the M15 for evaluation.
This review originally appeared on Audioreviews.
Price, while reviewed: $250. Can be bought from Questyle’s Official Website.

PACKAGING AND ACCESSORIES

The packaging is minimal, while the accessories are basic. You get a type-C to type-C cable by default. For Apple users, the lightning cable is sold as a separate bundle for USD$20 premium. There is also a nice leather case that you can purchase separately.

BUILD QUALITY

Questyle opts for a CNC-milled aluminum chassis with a see-through acrylic window for the M15’s design. It’s a simple yet effective design decision to go for a see-through top, as it makes the M15 stand out without going overboard. Questyle is not new to this, as many of its desktop products offer an acrylic top for those so inclined.

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In terms of inputs and outputs, things are decidedly simple. The type-C port allows USB connection while the 3.5mm and 4.4mm jacks offer unbalanced and balanced connections respectively. The balanced output sounds markedly better as an aside, but that is the case for nearly every dongle that offers a balanced output.

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There is a button on the side for gain control, and that’s about it. No volume or playback buttons are there which might be an issue for some. There are two LEDs on the PCB that shines through the acrylic, one for gain level and another is the file type indicator.

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Overall, a very simple yet elegant design that panders to my inner-geek thanks to that PCB that’s been laid bare.

HANDLING

At 61.8mm X 27.2mm X 12mm dimensions, the M15 is not the most innocuous of dongles in terms of size. However, I find it to be fairly practical on the desk and the low 25g of weight makes carrying it around easy enough. Even after prolonged usage, the M15 does not get hot which is another plus.

QUESTYLE M15 INTERNALS

Questyle has a knack for making pretty PCBs. Even the desktop DAC or amps have exceptionally clean PCB layout, and the M15 is no exception. Thanks to the acrylic window, all of it is in plain view. Apart from the ES9281AC DAC chip and the aforementioned status LEDs, you can also see the two SIP (system-in-package) current mode amp modules. Each module handles one channel.

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There is also a TOREX power management unit that keeps the M15 inactive when no music is playing. In terms of specs, you get a really respectable 0.0003% THD and <-130dB SNR. Then you notice the output power specs and things just do not add up. A measly 22mW into 300ohms? Surely that cannot be right?

In terms of the actual “sound pressure” produced, that indeed seems to be misleading. The M15 can drive most dynamic driver headphones and nearly every single IEMs out there. Only issue is that for best performance, you need to use a laptop as the source. The higher current from the USB ports enable greater dynamic swings.

Speaking of dynamic swings, the SE out can have almost 2Vrms voltage swing from the single-ended out, and about 3.8Vrms from the balanced out. You can connect the M15 to a pair of powered monitors in a pinch and use it as a DAC/pre-amp combo. Just make sure to put the volume at max on the DAC side.

All in all, respectable measured performance, except for the amp specifications which do not really add up to real world experience.

TONALITY AND TECHNICALITIES

As always, it’s difficult to simply talk about the “tonality” of a source gear rather than specific pairing notes. That being said, the M15 has certain “characteristics” that shine through no matter which IEMs or headphones you connect on the other end.

The first thing you notice is the resolution, and how easily the M15 delineates between instruments. Rest assured, the amount of perceived details on the M15 eclipses any other dongle under USD$300. Minute details are pushed to the forefront, making it easier to analyze and dissect tracks. If it’s resolution and precision you want, M15 is practically peerless.

Such hyper-realistic rendition comes at the cost of two things: spatial qualities, and a tendency to be ruthless with poorly mastered tracks or bright/shouty gear. The M15 is unforgiving, though the lack of “etchiness” in the treble and upper-mids make it a potent option for borderline bright IEMs and headphones. The staging won’t be engulfing or stretched outwards, like it can be on some of M15’s peers.

Dynamics are good in terms of macrodynamic punch, though microdynamics are not as evident as they are on certain desktop sources (or even Questyle’s higher-tier DAPs).

Finally, the power output is ample for practically any IEMs out there. When connected to a laptop or desktop, the M15 is too powerful for most IEMs, in fact. I routinely found myself lowering the gain and/or lowering the volume on the desktop side. This is still not enough for power hungry monsters like Hifiman’s HE-6, for example, so for the pesky planars, you still need a more substantial setup.

PAIRING NOTES

I’ll try to keep this section short and sweet.

IEMs that paired well with the M15: most of them, but highlights include Sennheiser IE 900/200/300, SoftEars Turii, Final E3000/A5000/E4000, JVC FW1800/FW10000/FDX1, Campfire Holocene/Andromeda 2020/Solaris.

Headphones that paired well with the M15: not the absurdly power hungry planars, including the likes of HE-6 (and Susvara, by extension, though I fail to understand why anyone would try to run Susvaras off of a dongle), Sennheiser HD800S (too bright), and Beyers (same issues as the Senns). The HD650 had a good pairing though it lacked the liquid smoothness you get off of tubes or high output impedance sources.

Hifiman HE-400i and Arya sounded exceptional through the M15, and if you own the Arya Stealth (or even the newer Arya Organic), the M15 will be more than enough to do justice to their resolving prowess.

SELECT COMPARISONS

I have pitted the Questyle M15 against every single “hyped” or well-regarded dongle that has been released so far. None of them are as resolving, period.

IMG_9825.jpg


Quloos MC01 gets close at the cost of sounding edgy in the treble and artificial throughout. Apogee Groove has better rendition (and sense) of space, but it sounds a bit veiled in the bass and treble comparatively. The Cayin RU6 are too smoothed out, while the Cayin RU7 opt for a more relaxed, engulfing, and timbrally-accurate presentation than going after raw details.

IMG_9873.jpeg


Lastly, the L&P dongles (W2 and W4) do better in terms of microdynamics but fall flat in every other aspect. The output power is lacking compared to the M15, and once again – not as resolving.

CONCLUDING REMARKS

I received the Questyle M15 back in November, 2022. At the time of writing this review (end of July, 2023) the M15 managed to ward off every single competition by the wayside.

It’s a remarkable achievement in the age of rapid-fire chi-fi releases, where even the parent brand makes its 6 months old “flagship” redundant by releasing something new and “improved”. The M15 is here to stay, and shall remain one of the best, if not the best DAC-Amp dongles out there for the foreseeable future.

The only caveat is the nature of the sound itself – it may become “information overload” for those accustomed to relaxed and laid-back tuning. With certain IEMs, the treble region can sound exaggerated and become bothersome in the long run.

These caveats apply to most, if not all products though, and the M15 achieves the one thing it set out to accomplish: the crown for the most “effortlessly resolving” DAC-Amp dongle out there. Questyle captured lightning in a bottle with the M15, and I hope the spark does not go out anytime soon.
hokagoteatimereviews
hokagoteatimereviews
Nice review 🙂

I love the m15, but if I was a daily user i would be a bit worried of that beautiful glass window. 😅

Again thats just me though.
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Quokka
Quokka
WARNING: Last month I ordered a Questyle M15 Dac and the Protective Leather Cover (grey) directly from the Questyle website. Last week my package arrived but was missing the Protective Leather Cover (US$25). I have since sent them numerous emails advising them of the missing cover and requested one to be sent. All of my emails have been ignored so far as I have not had any reply from Questyle. I’m very disappointed by the lack of communication and poor customer service from Questyle
Quokka
Quokka
UPDATE: After no response from Questyle, I lodged a dispute case with PayPal and have received a refund of US$25 for the missing item.

Hooga

100+ Head-Fier
Best in slot
Pros: Balanced output: outstanding spatial reconstruction, spectacular instrument separation, great imaging, bilaterally extended, dynamic, powerful sound
Elegant, warm-ish musicality
Well implemented High Gain option
MQA full decoder (MQA fanbois can rejoyce)
Moderate host power consumption
Modest price for this sound quality
Cons: Single ended output: dull, compressed, underwhelming
Modest accent on midbass is a step away from tonal neutrality (some may find this not a con).
Easily picks up RFI when paired to a 4G-connected phone
No ASIO driver. No Direct DSD output support by Roon on Windows
Not fully supported by ALSA. No Direct DSD output support by Roon on Linux, either
After a very unfortunate first try (the review unit which was kindfully sent to me by the manufacturer was stolen at my door), I finally got an M15 unit which I quite oddly found for a very good price 2nd hand in Japan. This second package reached me regularly so I can finally assess this device which already collected convinced cobloggers' praises.

As there already is a comprehensive article about M15 on Audioreviews, I will entirely skip a general description of the device features as it would be needless repetition. I will also be succint on most sound impressions.

I'm going to focus on some detail which are not covered in the previous piece, and/or on aspects for which I have a different opinion.

M15 costs € 249 + freight on the manufacturer's website.


Miscellaneous good stuff and caveats


Good High Gain option


Unlike what happens on so many other devices I heard, M15's High Gain option is not chastising in terms of dynamic range compression. The effect is indeed very modest, which makes HG a totally viable option whenever one feels like adding some more early juice delivery to one or another driver.

Bad Single Ended output


It is so obviously duller and noisier compared to the Balanced option to be totally unworthy of such an otherwise outstanding product. To give a vague idea, it's roughly on quality level of M15's cheaper (120€) sibling, the M12 - which quality, at that price level, is trounced by the like of E1DA 9038D.

This means that one cannot elect the M15 as its "only" dongle if he/she has one or more drivers with single ended connections to support. Too bad.

Spectacular sound, if not totally uncolored


M15's sound is first of all grand (spatially), and immediately after that it's clear and detailed. Instrument separation and layering are just spectacular - which paired with its space drawing capabilities make for a really uncommonly good imaging and "sense of immersion" into the outcoming sound.

M15 is not uncolored in terms of tonality. There is some added accent on midbass notes - which is if you wish part of the "usual" compromise "musicality vs purity". The situation comes out obvious when comparing M15 with E1DA 9038SG3: the two offer equal bilaterally extended sound ranges, with the latter's bass staying faster, "more technical", therefore also "less expressive" in a sense.

9038SG3 is however a step under M15 in terms of spatial reconstruction, with particular regards to depth. Layering is also a bit less refined - and that's mainly why M15 comes across overall "more musically pleasing" compared to 9038SG3.

Powerwise 9038SG3 is better vs very low impedances: in the E5000-acidtest 9038SG3 beats M15 in terms of bass control and overall clarity. It's fair to observe that 9038SG3 remains the best option around, and by far so, when the available budget is like half M15's asking price.

In its being "exquisitely musical if unpure" M15 can't but recall Groove in a sense. In Apogee's dongle case sound colouring is even more marked, and comes with furtherly higher capability in terms of stage drawing - depth and height most of all. The two devices are not effectively comparable though - mainly due to Groove's internal architecture making it the odd ball it is - read my piece for the full reasons why.

Annoying RFI sensitivity


When paired to a smartphone connected to the 4G cell network M15 easily picks up RFI (Radio Frequency Interference) when within approx 10cm from the phone. The "solution" is using a non-ultrashort USB-C cable for the connection, but a problem still remains when you walk around with your phone + the M15 in a coat's pocket...

By comparison, E1DA 9038D behaves very similarly, E1DA 9038SG3 is instead virtually immune to such RFI.


Oddly lacking Direct-DSD support on non-mobile OS


While M15's USB interfacing is fully supported by Android, not the same happens when the device is plugged onto a Windows or Linux host.

For Windows, Questyle does not make an ASIO driver available (yet?). M15 can therefore be used only on "WASAPI Exclusive" mode. Which means there's not way to have access to direct DSD transfers (Wasapi only supports PCM).

For Linux the situation is even wierder (if not unique). M15 is apparently not fully supported by standard ALSA (Advanced Linux Sound Architecture) and the end result is that Roon Bridge on a Linux server does not offer Direct DSD support onto M15 when locally connected to it. Not the first time it happens to me - 9038D and 9038SG3 suffer of the same issue.




Considerations & conclusions


It's very simple: Questyle M15 is "the" DAC/AMP dongle to have if one has 250-300€ to spend, and has balanced connectivity options for all its drivers.

It's got superb sound clarity and body, very good spatial reconstruction capabilities, very good power management and strong power output.

In terms of overall sound experience M15 easily beats all standalone budget and mid-tier DAPs I happened to audition or own, the ones starting to represent an evident upgrade to it being nothing short of Questyle's own QP1R, or Lotoo's Paw 6000 and Gold Touch, or Cayin's N8. Seen from this angle M15 carries a very reasonable price tag.

The sole serious caveat to mention for me about M15 is its Balanced output option being the sole one delivering good quality. Whoever wants or needs a Single-ended source wouldn't be as satisfied with M15 (and its price).

M15 is rightfully stuck on Audioreviews' WoE, and determines the passage of Earmen Sparrow and L&P W2 to the relevant Past Excellences section therein.

This article originally appeared on audioreviews.org, here.
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P
pokvin
Why does the balanced output sound so much better than the single ended?
Pirastro
Pirastro
It doesn't. I have the M15 and the balanced output is just louder. In fact, I think I prefer single ended output with IEMs. AND, the single ended sounds significantly better than the output of the M12, which I also have.
n00kie
n00kie
As you mentioned the bad SE output. Can I connect the M15 with a 4.4 mm to RCA cable to my desktop headphone amp to get full potential?

Bitsir

100+ Head-Fier
Questyle M15 | Super Short Sound Review | Speaker? Yes! Headphones/IEMs? Nah
Pros: + Great dynamics, confident & powerful
+ Sheer microdetail retrieval
+ Digs deep into recording, reveals tonal shifts well
+ Unlocks previously hidden technical ability of whatever is plugged into it
+ 3.5mm output is 99% as good as 4.4mm output
Cons: - Very narrow, cramped soundstage dimensions
- Overly analytical, distant sound presentation, unengaging
- Introduces "sonic walls" for headphones and IEMs, the opposite of immersive
- Needs to be paired with something warmish or the end result will sound clinical & artifical indeed
The Questyle M15 is great for active speakers but I do not like it for headphones/IEMS. I find it sounds overly sharpened & almost unnatural. There is no reason for it to sound as cramped as it does. Anyone who uses this when reviewing headphones/IEMs and say they find the stage to be only okay or small - don't trust it. This thing imparts its own flavour and shrinks the stage. The absolute majority of people want immersiveness for headphone/IEM listening and this is antithetical to that effect.
o0genesis0o
o0genesis0o
It’s amazing how you convey all the necessary info in such a short review ( and destroy my curiosity for M15 in the process) :dt880smile:
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Bitsir
Bitsir
I'm glad I could help you save some time and money. I've tried many dongles at this point. The M15 is my least favorite, even though I admit it has the best detail so far.

My absolute recommendation is the me Xduoo Link2 Bal which has THE widest stage and most immersive sound out of all dongles I've tried.
amanieux
amanieux
so you did not like m15, what other dac do you recommend (for iems exclusively) ?

SenyorC

100+ Head-Fier
Ending 2022 on a very good note!
Pros: Sound, aesthetics, build quality, performance...
Cons: Price (depending on your budget)...
DSC_7559.JPG


The Questyle M15 has been sent to me by Questyle in exchange for the publication of this review. No specific requests or comments have been made and, as always, I will aim to be as sincere and unbiased in my review as is humanly possible.
You can find the official page for the M15 here: https://www.questyle.com/language/en/m-15/

As always, this is a non affiliate link.

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Intro…

As this is going to be my last review of 2022, I wanted to end the year on a positive note, therefore, although I have been using the M15 for a while, I have saved the review until now. That is already an indication of what I think about the M15 but I am going to explain in detail what it is that has drawn me into this little (depending on what we compare it to) dongle.

Earlier in the year I reviewed the CMA15, which was (is) an amazing product, offering a lot in a single package even if the price is not exactly budget friendly (depending on your budget of course, there are much more expensive things out there).

Around the same time, Questyle launched the M15, a small dongle that is powered by USB from the host device, which got a lot of favourable opinions. I didn’t get a chance to try it out at the time that it was recently launched and to be honest, while I was interested, I really was not in need of a dongle style DAC. As you all know, my main portable set up is the iFi Gryphon, with the Go Blu being my pocketable option and when I really need to go smaller, well, I have a bunch of Apple dongles stored in all kinds of places which do the job.

I did try out a few other dongles, the most notable probably being the S9 Pro and the iFi Go Bar, and while I liked the Go Bar, I didn’t really feel that it gave me anything that I didn’t already have.

Fast forward some months and Questyle very kindly offered to send me the M15 and I was happy to give it a try. As a fan of the CMA15, I was interested to see what the brand could offer at the other end of the scale, in a tiny package that retails for just under 235€ (at the time of writing this review). Now that is not exactly a budget offering either (although it is a little cheaper than the iFi Go Bar) and I expected it to be good, but I wasn’t really counting on liking it as much as I actually do.

So, enough rambling for this year, let me get on with my last review of 2022 and explain what it is that I like about the Questyle M15.

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Presentation…

There is nothing really notable about the presentation of the device. It arrives in a small black box, well protected by the foam surround, and the only other accessory is a short (well made) USB-C to USB-C cable. As I said, nothing really to mention.

What is worth mentioning is the protective cover that Questyle included in a separate small box (this one white) and is available as a pack on their website for no extra cost (again, at the time of this review). The sleeve is made of leather and is available in a selection of colours, the one I received being light brown (something I am fond of).

DSC_7489.JPG


Build and aesthetics…

While the build quality seems to be very good, where the M15 stands out from the rest is in aesthetics. One side of the unit there is a transparent window that allows us to see the internals of the unit, that is the circuit board etc. While seeing a circuit board may not sound like much of a big deal, I like it, and it also stops us wondering about what level of workmanship may be inside the device. They also mounted the indicator LEDs on the board so they are visible through the window.

As far as the case, it is also very well built and has an open side to it, allowing us to still see through the window of the device. It is a very good fit and protects the device well, except for the open side of course. I am not sure how the window will stand up to scratches over time but I’m sure it would be easy enough to adapt a small piece of glass protector if it is something that worries you.

There is also a cut out on the side of the cover which allows easy access to the gain switch. This is something simple enoguh but not all brands actually take it into consideration.

DSC_7476.JPG


Functionality…

There really isn’t anything complex about the M15 that would need explaining, but let’s go over it briefly anyway.

On the bottom of the unit we have the USB-C connector which is where our source device connects. On the side, we have the gain switch that slides to either low or high gain. On the top of the device we have a 3.5mm unbalanced output, together with a 4.4mm balanced output.

There are two LEDs on the circuit board that are visible via the transparent window. The first shows the set gain level (green for low and red for high). The second, which will only light up when the device is playing and has earphones connected, shows us the format of the file we are listening to, green indicates 48kHz or less, red indicates 88.2kHz PCM (or above) and DSD64 to DSD256.

That is it. Not much to explain.

I have tried the M15 on multiple Android devices and on multiple PCs and while there was an issue with MQA playback on Android at first, an update to Tidal fixed the issue, so the blame can obviously be directed at Tidal.

One thing I have found as an issue is that, when using the M15 connected to a Windows 10 PC (I don’t have any 11 machines, thankfully 😉 ) and running Tidal in exclusive mode, each time there is a track change, the volume jumps to 100%. This is something that could be a problem and I recommend that you either avoid Tidal in exclusive mode on PC or at least try it without your favourite IEMs connected (and certainly not in your ears) to see if it happens also on your machine. I think this is something related to the Tidal software as it has not happened to me with any other media player software (nor with Tidal on Android) but is certainly worth being aware of.

DSC_7424.JPG


Sound…

Judging the sound of a good device (and the M15 is certainly that) is something that I find difficult, as I can never be 100% sure of what I am actually hearing and what is just something that my brain thinks I am hearing. I have said many times that the brain is the most important part of audio, as we can not only interpret things in a different way, but can also experience things that may not actually be there.

Yes, it is possible to do triple blind ABX tests to see if we can really notice a difference between two amplifiers or DACs, and I have no doubt that the vast majority of us would fail, but at the end of the day, listening to music is about enjoyment (at least for me). That means that if I am listening to something and I really enjoy the sound, then I really don’t care if 95% of the sound is just my brain telling me that I am hearing what I want to hear, I mean, at the end of the day, I am doing just that, hearing what I want to hear.

In the case of the M15, I have been using it with quite a few sets of IEMs that I have been testing over the past weeks, plus some more that I will review soon, and I have to say that I really enjoy what the M15 has to offer.

It may not be the most powerful of devices, although I do not have measurements, but in comparison to the Go Bar, it does seem to have a lower output level. However, for IEMs, I have not found that any of the IEMs I have tested via the SE output have needed me to switch to high gain, much less in balanced mode.

As an example, I have mainly been using the M15 connected to my android tablet, using UAPP, and my usual listening levels have been between -24dB and -26dB (depending on track and IEMs used), so plenty of power left. With planar IEMs, such as the Talos or S12, I have been using the balanced output but have not noticed any lack of power or performance with these IEMs.

It also does a decent job with over ears, especially easier to drive ones. With the HD6XX I was very pleasantly surprised with how well they work with the M15. I wouldn’t say that it is the best I have ever heard from the HD6XX (it won’t be replacing the Feliks) but it is plenty for my listening levels and the performance is better than a lot of other options I have tried with these headphones. With more difficult to drive planars, such as the Arya v2, it again reached my listening levels without issue, although I don’t feel that it was quite capable of driving them to the best of their abilities (which is to be expected from a dongle).

The sound itself I find to be extremely detailed but never harsh. Now, as I already said, these are completely subjective opinions, so take that for what you will, but in comparison to my main IEM set ups, the Gryphon and the Go Blu, I find that the M15 seems to be a little more airy, giving a sensation of more detail and a little less warmth.

However, even if it presents less warmth than the iFi options, it still stays a long way from being harsh or cold, something that I did find with the S9 Pro for example. The S9 Pro I also found to be something that potrayed lots of details, yet at the same time, I got the sensation that the details sounded forced, as if they were being pushed at you. The M15 gives me no such sensation, is presents the details in a way that they are very easy to focus on but never seem to be “in your face”.

With IEMs that can have a little bit of harshness in the higher ranges, or with tracks that are also on the harsh side, I don’t find that the M15 adds any extra harshness at all. With tracks and IEMs that are on the other side of the scale, a little too warm (or even bloaty) in the low end, I find that the M15 actually seems to tighten it up a little, without actually removing quantity.

If I had to explain the overall sound of the M15 in one sentence, it would be “clean, neutral, natural and smooth”.

DSC_7443.JPG


Conclusion…

As I said at the beginning of this review, I wanted to end 2022 on a positive note and the experience I have had with the M15 is nothing but positive. I have paired it with a lot of different combinations and while it wouldn’t be my first choice for power hungry over ears, for everything else I have found that it is just a wonderful little device.

I am someone who prefers cables when possible and while I really enjoy the Go Blu for what it gives me in a bluetooth package, when connected by cable, I much prefer the M15, at least for the IEMs that I use regularly (and those that I have been testing) with the music that I listen to.

It is not going to replace the Gryphon as my main test device for reviews, as the Gryphon has (apart from great sound) so many other functions that make it a perfect (trans)portable device. However, for a compact device that provides excellent sound, the M15 is going to become a main part of my listening experience on the go (or even just relaxing on the sofa).

Therefore, with the Sennheiser IE600 connected to the Questyle M15 and my favourite albums, I conclude my reviews of 2022 in the best way possible!

_________________________________

As always, this review is also available in Spanish both on my blog (www.achoreviews.com) and on YouTube (www.youtube.com/achoreviews)
S
Surdzo
I also use M15 with ie600(4.4), ie100PRO(3.5), Nuemann NDH20 (3.5 soon arrive balanced cables so will try with 4.4 port) same goes for Sennheiser HD650. I also have Xduoo link2 bal max (new version), Hiby FC4 and apple dongle 3.5mm have heard my gear on my Topping L30ii and other dongles but M15 is by far the best I have ever heard especially with Sennheiser IE600 it is PERFECT MATCH.
About the M15 beside it is almost perfect dongle dac/amp there are some issues
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S
Surdzo
1. With Tidal is very hard to adjust volume especially in "Exclusive mode" it is pain in the a** and if you not use "EM" there is not MQA or at least magenta light just red or sometimes even green.
2.Sometimes also on Tidal in "EM" you will get red light on one song other time just green (Same song same playlist) and when switch to "System controlled" output from green goes to red but than there is not magenta on MASTER track
so it is bit confusing and annoying all this on both windows laptops one run 10pro other 11 so doesn't matter. On iPhone everything functioning perfect green is green red is red magenta is magenta simply no problem at all.
S
Surdzo
Now the interesting thing.
Both Neumann NDH20 (150 Ohms) & Sennheiser HD650 (300 Ohms) sound better on M15 (High Gain) than Topping L30ii paired with Marantz PM7000N (Asahi-kasei AK4490EQ DAC) thru QED Performance Audio Graphite RCA cable and Marantz PM7000N thru its own 6.35 output directly. No matter iPhone or Laptop connected and all that on SE 3.5 I just could imagine the difference when balanced cables for both headphones arrive :)
Xduoo link2 bal max and Hiby FC4 also very good dac/amp but Questyle M15 is from another planet and worth every penny. whatever you put on M15 it sounds much much better than anything you have heard before.
I'm really considering to order extra few just to have peace of mind if anything happened with it in future or Questyle simply discontinue this model :D
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Ichos

Reviewer at hxosplus
Divine current on the go
Pros: + Musical and organic sounding
+ Realistic timbre and minimum digital glare
+ Excellent technicalities
+ Crystal clear and transparent
+ Dynamic and impactful
+ Dead silent and free of EMI noise
+ Can drive efficient headphones
+ Low power consumption
+ Stays cool even after hours of use
+ Unique appearance
+ Excellent build quality
Cons: - Lack of on-board volume control and hardware buttons
- Not as powerful as the competition
- Carrying case and lightning cable are extra
- Bright LEDs
The review sample was kindly provided free of charge in exchange for an honest review.
I didn't receive monetary or any other kind of compensation and I don't use affiliate links.
The price of the M15 is $249 and you can order it directly from Questyle shop or all authorized dealers around the world.

Questyle

Questyle Audio is dedicated to the research of high-tech lossless audio systems with perfect sound aesthetics and convenient listening experience, and provide the corresponding products, system solutions or key components according to customer requirements.
They are famous for their Current Mode Amplification topology that uses current, instead of voltage, to amplify audio signals.
Their CMA Fifteen is one of the most awarded and well regarded all-in-one systems thanks for its unparalleled performance as you can find out by reading the related review.
After finishing the CMA Fifteen review I was very curious to find out how the Current Mode Amplification performs in a portable device so I contacted Questyle who were very responsive and kind enough to arrange a sample.

IMG_20221124_152538.jpg


Questyle M15

The Questyle M15 is a USB DAC/amp dongle containing two of Questyle’s patented CMA (Current Mode Amplification) SiP modules, for a total of four CMA amp engines.
This quadruple drive amplification circuitry gives an outstandingly strong output that can drive almost any headphone.
Questyle’s Current Mode Amplifiers are characterized by their small footprint, low voltage operation, and minimal power consumption.
Current Mode amplification has a naturally low impedance, affording the M15 a bandwidth up to 1MHz and distortion as low as 0.0003%.

m15.png.a75f1604650f897e9c47dc8705779d6a.png


The M15 supports both unbalanced (3.5mm) and balanced (4.4mm) outputs with a manual gain adjustment via the slider on the side, which makes it easy to choose high/low gain depending on the connected headphone.
The M15 features the highly acclaimed ESS ES9281AC flagship DAC chip to do the decoding and can handle up to PCM384kHz/32bit, DSD256 and full MQA unfold.
The M15 also uses a TOREX, high-efficiency, power management unit for low power consumption from the host device without getting overheated.

IMG_20221124_152726.jpg


Appearance and build quality

The M15 has a minimalistic design with a black metal housing that is made from CNC machined aluminum and a transparent glass cover which allows for the internal PCB to be fully visible.
A very innovative design that differentiates the M15 from the competition giving it a uniquely looking appearance.
Build quality and finish are excellent, there are no rough edges or sharp corners but I have some reservations about the durability of the glass.
The 61.8x27.2x12mm measuring M15 is compact and lightweight, at least for a dongle with two headphone outputs.

IMG_20221124_152804.jpg


User interface

This is a simple to operate device, no drivers are needed, the only thing you have to do is to plug it to the host device with the supplied detachable cable to the USB type-C port and then your headphones to either the single ended or balanced outputs.
The device will power itself only when a headphone is plugged in so you can leave it hanging from your phone without consuming power if you have your headphones unplugged.

The M15 is lacking an on-board volume control so you are restricted to your phone's steps for volume adjustment which is not that ideal.
Inside the unit and close to the USB port there are located two indicator LEDs that are quite bright.
One is for displaying the sample rate (Green ≤ 48kHz, Red>48kHz or DSD and Magenta for MQA) and the other for the gain (Red=high, Green=Low).

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Accessories

Inside the box you are going to find two short USB cables of high quality.
USB-C to USB-C and USB-A to USB-C.
A lighting cable and a premium leather case are available as extra purchases.

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Power output

The M15 was left playing music for about 100 hours in order to settle down.
During the evaluation period I used various headphones and earphones like the Focal Clear Mg, Sennheiser HD660S, Meze 109 PRO, FiiO FDX and Unique Melody Mext.
All headphone cables are from pure silver made by Lavricables.

With a maximum output voltage of 1.895Vrms from the 3.5mm jack and 2.624Vrms from the 4.4mm, the M15 is not the most powerful dongle when considering that most of the competition can usually do 4Vrms from the balanced output while the iFi Go bar can go as high as 7.5Vrms.
But sometimes lab measurements can be deceiving and the truth is that the M15 provided plenty of juice for driving efficient headphones like the Focal Clear Mg and the Meze 109 PRO.
Background noise is pretty inaudible and the M15 is well shielded so it doesn't pick electromagnetic interference.
The M15 stays completely cool even after hours of continuous use and it has a relatively low power consumption.

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Listening impressions

Plain and simple, the M15 is the most naturally sounding ESS dongle that I have reviewed so far with the less (if not completely absent) digital glare while retaining all of the famous ESS transparency and excellent technicalities.
It seems that the "current mode amplification" modules are making a great job into producing a very musical sound signature with an analogue-like and organic timbre.

Listening with the M15 is an enjoyable and engaging experience that is characterized by the surplus of musicality.
The tonality is realistic with plenty of colorful overtones that help instruments and voices to sound harmoniously intense and complete.
At the same time the M15 is a competent technical performer with supreme fidelity, absence of coloration and frequency response irregularities, petty thundering dynamics, excellent resolution and crystalline clarity.
There is no kind of music that is not suitable for the M15 while headphone matching is really not an issue because the M15 makes sure that you are listening to your headphones and not the device itself.

The bass is deeply imposing, fast, precise and controlled with excellent layering and definition.
The texture is not too visceral but not lean either, balanced would be the word to use while dynamics sound contrasted and impactful.
Mid-range consistency is great; the sound is coherent and articulated with a lush and rounded texture without becoming warm or romantic.
This is the part of the frequency range that has the richest harmonies and the purest timbre helping instruments and voices to sound very alive and close to reality.

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The treble extension is amazing, the M15 is lively and sparkling sounding with excellent detail retrieval and plenty of airiness but without any of the brightness and forwardness that are usually associated with most ESS DAC implementations.
Smooth enough, without sharpness or edginess and very controlled when it comes to digital glare, the M15 is the kind of DAC that is heartily recommended for all day listening without causing treble fatigue.

The soundstage, given that you have the right headphone, can become very speaker-like at least as far as a dongle can go.
It is grand sized with sharp imaging and tactile arrangement of the performers with plenty of spatial information and natural reverb.
The listener feels like sited in the second row of the concert hall making the M15 ideal for listening to large scale symphonic and choral works.

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Compared to the iFi Go bar ($329)

I consider the iFi Go Bar (and the Cayin RU-6 ) the references when it comes to musicality and organic timbre so a comparison, with at least one of them, was pretty inevitable.
Comparing the Go bar with the M15 proved that are on the same league of musical presentation with some minor differences.

The M15 has the lead in technicalities because it offers better clarity, it sounds more defined and resolving, it has faster transients, more contrasted dynamics and impactful bass.
But it sounds relatively drier when compared the more organic, tube-like and fuller sounding Go bar.
Additionally the Go bar feels more relaxed and loose around the notes, not as fast and not that firm or controlled.
The Go bar has a more holographic soundstage presentation but the positioning of the listener is closer, more intimate, almost next to the performers.

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On the non-audio related stuff, it is the minimalistic M15 against the full featured Go bar which offers four digital reconstruction filters, XBass+ and XSpace analogue processing modes and iEMatch.
The Go bar has also an on-board volume control and physical buttons and it is more powerful than the M15 but with the disadvantage that it is not that power efficient.
The Go bar is about $80 more expensive than the M15 but the package includes a lighting to USB-C cable and a carrying case.

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In the end

The Questyle M15 is not only the most uniquely looking USB DAC dongle among the competition but is also the most uniquely sounding because it manages to combine top level technicalities with the most musical and organic sounding character almost surpassing every other USB DAC dongle.
Very efficient and simple to use, the only thing you have to do is to plug your headphones and let be carried away by the divine current into the most musical adventure.

Test playlist

Copyright - Petros Laskis 2022.

GojiFi

New Head-Fier
𝐐𝐮𝐞𝐬𝐭𝐲𝐥𝐞 𝐌𝟏𝟓: Deus Ex Machina
Greetings! 💨🦖

This is a review of the Questyle M15, which Questyle themselves have provided me to review.

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DISCLAIMER: I WAS PROVIDED THE UNIT IN EXCHANGE FOR A NO-FRILLS, UNBIASED REVIEW. I AM NEITHER PAID NOR COMMISSIONED TO PROVIDE A SKEWED REVIEW.

This review for the Questyle M15 marks Goji’s debut in reviewing a series of gear that can be considered as an audiophile’s best friend: the dongle. This debut in starting to review dongles has been grandiose so far: the Questyle M15 is an absolute god when it comes to outputting every song you throw at it in the clearest and most beautiful way possible. It has the power to push most IEMs to their upper limits, resulting in a very versatile experience, no matter how huge your collection is. I couldn’t describe any faults with how good the M15 is, as long as you have the pocket/wallet depth that it requires.

𝙋𝙧𝙞𝙘𝙚
$249.99 (USD)
~₱14,254.80 (PhP)

𝙏𝙚𝙘𝙝𝙣𝙞𝙘𝙖𝙡 𝙎𝙥𝙚𝙘𝙞𝙛𝙞𝙘𝙖𝙩𝙞𝙤𝙣𝙨
𝗢𝗽𝗲𝗿𝗮𝘁𝗶𝗻𝗴 𝗦𝘆𝘀𝘁𝗲𝗺 𝗥𝗲𝗾𝘂𝗶𝗿𝗲𝗱:
- Android phone and pad: Android 5.0 and above;
- Apple cellphone: iOS
- Apple computer: mac OS
- PC: Win10 1803 and above;
𝗗𝗔𝗖:ESS flagship USB DAC chip ES9281AC
𝗗𝗔𝗖 𝗖𝗮𝗽𝗮𝗯𝗶𝗹𝗶𝘁𝘆:
- PCM:PCM: 32kHz – 384kHz (16/24/32Bit)
- DSD: DSD64(1Bit 2.8MHz) , DSD128(1Bit 5.6MHz), DSD256(1Bit 11.2MHz)
𝗢𝘂𝘁𝗽𝘂𝘁 𝗣𝗼𝘄𝗲𝗿:
- 3.5mm:RL=300Ω,Po=11.97mW, Vout(Max)=1.895Vrms,THD+N=0.00045%
- 4.4mm:RL=300Ω,Po=22.60mW, Vout(Max)=2.624Vrms,THD+N=0.00057%
𝗧𝗼𝘁𝗮𝗹 𝗛𝗮𝗿𝗺𝗼𝗻𝗶𝗰 𝗗𝗶𝘀𝘁𝗼𝗿𝘁𝗶𝗼𝗻:0.0003%
𝗣𝗹𝘂𝗴 𝗧𝘆𝗽𝗲: 3.5mm unbalanced, 4.4mm balanced

𝙋𝙖𝙘𝙠𝙖𝙜𝙞𝙣𝙜 💨💨💨💨🦖 (out of 5)

➡️ Presentation
The box of the Questyle M15 isn’t that extravagant nor far-reaching as the likewise-priced IEMs that I have unboxed in the past, but this one mean business right away. The packaging does not follow any trends in Chi-Fi; it really looks like it came from a big name in the industry in terms of how professional and elegant the packaging is. It does not flood the consumer with any grandiosity: it just means business. That’s how you say that the Questyle M15 will surely give its listener the best experience possible.

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➡️ Product
After a layer of paperwork, we are presented right ahead with the Questyle M15 in all its glory. There is just a layer of protective plastic covering the huge window for one to see the internals of the dongle, and it’s nothing short of breathtaking to see. It’s like looking at a McGuffin in futuristic sci-fi film, destined to carry some sort of data that holds the fate of the universe. Questyle’s logo is emblazoned on the rear side of the dongle, printed out in a minimalist yet recognizable way. There are no other visual flairs here and there in this product. Tt just focuses you look at the main attraction: the beautiful internal hardware that powers the beast.

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➡️ Particulars
After the layer that houses the dongle itself, the final one contains two cables: USB-C to USB-A and USB-C to USB-C. The dongle itself terminates at a USB-C port, so this is more than enough for one to use for his/her smartphone and PC needs. Questyle also graciously provided me with an extra cloth bag for travel and a USB-C to Lightning connector, which was helpful as I have an iPhone 6 Plus as my main phone as of the moment. The particulars may be spartan, but it’s more than enough to handle my own personal use of it from the gears that I have.

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𝘽𝙪𝙞𝙡𝙙 𝙌𝙪𝙖𝙡𝙞𝙩𝙮 💨💨💨💨💨🦖 (out of 5)
I haven’t tried out dongles before, but I have seen and handled many in the past years that I have been in this hobby. Let me tell you, the build of the M15 is just immaculate. There are no seams nor awkward connections that line the entirety of the product. The reason why I mentioned seams and connections is that those can easily open when an item is dropped. Any form of them is a structural weakness in any gear, even in IEMs. In lieu of this, the M15 is built like a small tank, able to take falls or hits without any hitch. It also has reliable plugs that provide that satisfying hefty click when you insert your 3.5mm or 4.4mm termination in it, ensuring that you have properly connected your audio gear into the dongle. It can be just a little bit awkward at first as it connects deeper than your ordinary smartphone or PC port, but it’s easy to get used to. I have also seen some reports of the switch for the low/high gain malfunctioning for some of those who own the M15; I haven’t personally experienced it in the few months that I’ve used it extensively. It still feels just as sturdy and as reliable as the first day I have got it, and never malfunctioned on me since.

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𝙐𝙄 (𝙐𝙨𝙚𝙧 𝙄𝙣𝙩𝙚𝙧𝙛𝙖𝙘𝙚) 𝙖𝙣𝙙 𝙀𝙖𝙨𝙚 𝙤𝙛 𝙐𝙨𝙚 💨💨💨🦖(out of 5)
I have had the chance to extensively use this dongle for a few months after writing this review, so I really had the time to experience every nook and cranny that the M15 offered to its user. First things first: this is definitely NOT for travel or outdoor use. The entirety of the dongle may seem small when you first handle it, but it is extremely clunky when you try to have a portable experience from it by inserting it to your chosen device and going out while it’s located in your pocket. This can be slightly solved by purchasing a longer cable to connect it to your device, but it results in a tangly experience that is also clunky to experience outdoors. The Questyle M15 is meant to be used indoors or in a more relaxed travelling environment (in a private car, in an airplane flight, etc.) because of its size in conjunction with its purpose as an extension of your device. But once you get the hang of it, you’ll realize its situational use and plan out your excursions accordingly.

On the other hand, the M15 easily connects to any device that I plug it in: may it be in my Samsung smartphone (Samsung Galaxy S8+), iOS (iPhone 6 Plus, iPhone X, iPad mini), and PC (HP Pavillion x360). It automatically detects the dongle AS LONG AS a gear is plugged into any of the inputs (3.5/4.4), as devices sometimes fail to recognize the M15 in situations when there is no gear attached to it. It already comes with software that’s compatible with most devices, though you have the choice to update its software version with an installer and data available on Questyle’s official website. Some said that there are changes in the sound signature of the M15 when it is indeed updated, but I cannot confirm nor deny it. I honestly didn’t perceive any noticeable differences, but if there is, it’s to the point that isn’t worth noting. The LEDs on the device also seamlessly switch between colors depending on the gain (low=green, high=red) and the file type/bitrate being processed (green=48kHz or less, red=PCM/DSD, magenta=MQA final unfolding). I have tested this out as I have file types of different kinds (MP3s, FLACs, DSD/PCMs, and Tidal for MQA), and it corresponds correctly to the files I throw at it.

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A gripe that I have with the M15 can be seen in its lack of any other options in terms of hardware switches/buttons rather than the low/high gain option. This would’ve benefitted from the addition of a volume button/rocker and a play/pause button as complimentary to the low/high gain switch. However, these decisions may have been scrapped to allow for the nice circuitry on display that is present on this device.

𝙎𝙤𝙪𝙣𝙙 💨💨💨💨💨🦖 (out of 5)

𝗠𝗨𝗦𝗜𝗖 𝗨𝗦𝗘𝗗:

𝘋𝘢𝘧𝘵 𝘗𝘶𝘯𝘬 - 𝘙𝘢𝘯𝘥𝘰𝘮 𝘈𝘤𝘤𝘦𝘴𝘴 𝘔𝘦𝘮𝘰𝘳𝘪𝘦𝘴 (𝘢𝘭𝘣𝘶𝘮)
𝘋𝘢𝘧𝘵 𝘗𝘶𝘯𝘬 - 𝘈𝘭𝘪𝘷𝘦 2007 (𝘢𝘭𝘣𝘶𝘮)
𝘋𝘢𝘷𝘪𝘥 𝘉𝘰𝘸𝘪𝘦 - 𝘉𝘭𝘢𝘤𝘬𝘴𝘵𝘢𝘳 (𝘢𝘭𝘣𝘶𝘮)
𝘋𝘶𝘢 𝘓𝘪𝘱𝘢 -𝘍𝘶𝘵𝘶𝘳𝘦 𝘕𝘰𝘴𝘵𝘢𝘭𝘨𝘪𝘢 (𝘢𝘭𝘣𝘶𝘮)
𝘛𝘸𝘪𝘤𝘦 - 𝘔𝘰𝘳𝘦 & 𝘔𝘰𝘳𝘦 (𝘢𝘭𝘣𝘶𝘮)
𝘛𝘸𝘪𝘤𝘦 - 𝘌𝘺𝘦𝘴 𝘞𝘪𝘥𝘦 𝘖𝘱𝘦𝘯 (𝘢𝘭𝘣𝘶𝘮)
𝘔𝘪𝘤𝘩𝘢𝘦𝘭 𝘑𝘢𝘤𝘬𝘴𝘰𝘯 - 𝘋𝘢𝘯𝘨𝘦𝘳𝘰𝘶𝘴 (𝘢𝘭𝘣𝘶𝘮)
𝘕𝘦𝘸 𝘖𝘳𝘥𝘦𝘳 – 𝘛𝘖𝘛𝘈𝘓 (𝘢𝘭𝘣𝘶𝘮)
𝘕𝘦𝘸 𝘖𝘳𝘥𝘦𝘳 - 𝘗𝘰𝘸𝘦𝘳, 𝘊𝘰𝘳𝘳𝘶𝘱𝘵𝘪𝘰𝘯, 𝘢𝘯𝘥 𝘓𝘪𝘦𝘴 (𝘢𝘭𝘣𝘶𝘮)
𝘗𝘰𝘳𝘤𝘶𝘱𝘪𝘯𝘦 𝘛𝘳𝘦𝘦 - 𝘐𝘯 𝘈𝘣𝘴𝘦𝘯𝘵𝘪𝘢 (𝘢𝘭𝘣𝘶𝘮)
𝘗𝘰𝘳𝘤𝘶𝘱𝘪𝘯𝘦 𝘛𝘳𝘦𝘦 - 𝘍𝘦𝘢𝘳 𝘰𝘧 𝘢 𝘉𝘭𝘢𝘯𝘬 𝘗𝘭𝘢𝘯𝘦𝘵 (𝘢𝘭𝘣𝘶𝘮)
𝘚𝘭𝘦𝘦𝘱 - 𝘏𝘰𝘭𝘺 𝘔𝘰𝘶𝘯𝘵𝘢𝘪𝘯 (𝘢𝘭𝘣𝘶𝘮)
𝘚𝘭𝘦𝘦𝘱 - 𝘛𝘩𝘦 𝘚𝘤𝘪𝘦𝘯𝘤𝘦𝘴 (𝘢𝘭𝘣𝘶𝘮)
𝘖𝘮 - 𝘈𝘥𝘷𝘢𝘪𝘵𝘪𝘤 𝘚𝘰𝘯𝘨𝘴 (𝘢𝘭𝘣𝘶𝘮)
𝘊𝘢𝘯𝘥𝘭𝘦𝘮𝘢𝘴𝘴 - 𝘌𝘱𝘪𝘤𝘶𝘴 𝘋𝘰𝘰𝘮𝘪𝘤𝘶𝘴 𝘔𝘦𝘵𝘢𝘭𝘭𝘪𝘤𝘶𝘴 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘦𝘭𝘭 𝘞𝘪𝘵𝘤𝘩 - 𝘔𝘪𝘳𝘳𝘰𝘳 𝘙𝘦𝘢𝘱𝘦𝘳 (𝘢𝘭𝘣𝘶𝘮)
𝘗𝘢𝘭𝘭𝘣𝘦𝘢𝘳𝘦𝘳 - 𝘏𝘦𝘢𝘳𝘵𝘭𝘦𝘴𝘴 (𝘢𝘭𝘣𝘶𝘮)
𝘋𝘦𝘢𝘧𝘩𝘦𝘢𝘷𝘦𝘯 - 𝘚𝘶𝘯𝘣𝘢𝘵𝘩𝘦𝘳 (𝘢𝘭𝘣𝘶𝘮)
𝘋𝘦𝘢𝘧𝘩𝘦𝘢𝘷𝘦𝘯 - 𝘖𝘳𝘥𝘪𝘯𝘢𝘳𝘺 𝘊𝘰𝘳𝘳𝘶𝘱𝘵 𝘏𝘶𝘮𝘢𝘯 𝘓𝘰𝘷𝘦 (𝘢𝘭𝘣𝘶𝘮)
𝘒𝘰𝘳𝘯 - 𝘒𝘰𝘳𝘯 (𝘢𝘭𝘣𝘶𝘮)
𝘒𝘰𝘳𝘯 - 𝘓𝘪𝘧𝘦 𝘐𝘴 𝘗𝘦𝘢𝘤𝘩𝘺 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘭𝘢𝘤𝘬 𝘛𝘰𝘯𝘨𝘶𝘦 - 𝘕𝘢𝘥𝘪𝘳 (𝘢𝘭𝘣𝘶𝘮)
𝘋𝘦𝘢𝘵𝘩 - 𝘏𝘶𝘮𝘢𝘯 (𝘢𝘭𝘣𝘶𝘮)
𝘋𝘦𝘢𝘵𝘩 - 𝘚𝘺𝘮𝘣𝘰𝘭𝘪𝘤 (𝘢𝘭𝘣𝘶𝘮)
𝘋𝘦𝘢𝘵𝘩 - 𝘛𝘩𝘦 𝘚𝘰𝘶𝘯𝘥 𝘰𝘧 𝘗𝘦𝘳𝘴𝘦𝘷𝘦𝘳𝘢𝘯𝘤𝘦 (𝘢𝘭𝘣𝘶𝘮)
𝘕𝘪𝘨𝘩𝘵𝘸𝘪𝘴𝘩 - 𝘖𝘯𝘤𝘦 [𝘙𝘦𝘮𝘢𝘴𝘵𝘦𝘳𝘦𝘥] (𝘢𝘭𝘣𝘶𝘮)
𝘕𝘪𝘨𝘩𝘵𝘸𝘪𝘴𝘩 - 𝘋𝘢𝘳𝘬 𝘗𝘢𝘴𝘴𝘪𝘰𝘯 𝘗𝘭𝘢𝘺 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘦𝘩𝘦𝘮𝘰𝘵𝘩 - 𝘖𝘱𝘷𝘴 𝘊𝘰𝘯𝘵𝘳𝘢 𝘕𝘢𝘵𝘷𝘳𝘢𝘮 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘦𝘩𝘦𝘮𝘰𝘵𝘩 - 𝘐 𝘓𝘰𝘷𝘦𝘥 𝘠𝘰𝘶 𝘈𝘵 𝘠𝘰𝘶𝘳 𝘋𝘢𝘳𝘬𝘦𝘴𝘵 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘦𝘩𝘦𝘮𝘰𝘵𝘩 – 𝘌𝘷𝘢𝘯𝘨𝘦𝘭𝘪𝘰𝘯 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘦𝘩𝘦𝘮𝘰𝘵𝘩 - 𝘛𝘩𝘦 𝘈𝘱𝘰𝘴𝘵𝘢𝘴𝘺 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘦𝘩𝘦𝘮𝘰𝘵𝘩 – 𝘋𝘦𝘮𝘪𝘨𝘰𝘥 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘦𝘩𝘦𝘮𝘰𝘵𝘩 - 𝘡𝘰𝘴 𝘒𝘪𝘢 𝘊𝘶𝘭𝘵𝘶𝘴 (𝘢𝘭𝘣𝘶𝘮)
𝘉𝘦𝘩𝘦𝘮𝘰𝘵𝘩 - 𝘛𝘩𝘦 𝘚𝘢𝘵𝘢𝘯𝘪𝘴𝘵 (𝘢𝘭𝘣𝘶𝘮)
𝘔𝘦𝘵𝘢𝘭𝘭𝘪𝘤𝘢 - ...𝘈𝘯𝘥 𝘑𝘶𝘴𝘵𝘪𝘤𝘦 𝘧𝘰𝘳 𝘈𝘭𝘭 (𝘢𝘭𝘣𝘶𝘮)
𝘔𝘦𝘵𝘢𝘭𝘭𝘪𝘤𝘢 - 𝘔𝘦𝘵𝘢𝘭𝘭𝘪𝘤𝘢 (𝘢𝘭𝘣𝘶𝘮)
𝘚𝘦𝘱𝘵𝘪𝘤𝘧𝘭𝘦𝘴𝘩 – 𝘛𝘪𝘵𝘢𝘯
𝘚𝘦𝘱𝘵𝘪𝘤𝘧𝘭𝘦𝘴𝘩 - 𝘊𝘰𝘥𝘦𝘹 𝘖𝘮𝘦𝘨𝘢

𝗡𝗢𝗧𝗘: 𝘐 𝘵𝘦𝘴𝘵 𝘦𝘷𝘦𝘳𝘺𝘵𝘩𝘪𝘯𝘨 𝘪𝘯 𝘣𝘰𝘯𝘦-𝘴𝘵𝘰𝘤𝘬 𝘤𝘰𝘯𝘥𝘪𝘵𝘪𝘰𝘯. 𝘐 𝘈𝘓𝘞𝘈𝘠𝘚 𝘶𝘴𝘦 𝘸𝘩𝘢𝘵 𝘪𝘴 𝘪𝘯𝘤𝘭𝘶𝘥𝘦𝘥 𝘪𝘯 𝘵𝘩𝘦 𝘱𝘢𝘤𝘬𝘢𝘨𝘦 𝘵𝘰 𝘢𝘷𝘰𝘪𝘥 𝘢𝘯𝘺 𝘪𝘯𝘢𝘤𝘤𝘶𝘳𝘢𝘤𝘪𝘦𝘴 𝘰𝘯 𝘩𝘰𝘸 𝘐 𝘳𝘦𝘷𝘪𝘦𝘸 𝘵𝘩𝘦 𝘪𝘯𝘯𝘢𝘵𝘦 𝘴𝘰𝘶𝘯𝘥 𝘰𝘶𝘵𝘱𝘶𝘵 𝘰𝘧 𝘢𝘯𝘺 𝘨𝘦𝘢𝘳 𝘵𝘩𝘢𝘵 𝘐 𝘵𝘦𝘴𝘵.

➡️ Signature
I will be honest and upfront in saying that I am in no means an expert in reviewing dongles. I am more adept in my homecourt of reviewing IEMs and other gear that output the sound directly to my ears rather than the one that processes it. However, I can definitely tell that the Questyle M15 is doing wonders and miracles with whatever is put inside of it. Every aspect of the audible frequency is improved and polished to absolute perfection. As the title of this review indicates, the M15 feels like a deux ex machina in stories and movies: an item/event that saves and defeats every plot hole or antagonist present in just a blink of an eye. Both of its gain modes properly drive all the gears that I have, which can be a testament that it can power anything that you have, as long as it’s not one of those higher priced/vintage planar/EST headphones that has ridiculous resistance values. That’s how good this dongle is when put to every test, and it does it without breaking any sweat.

If I were to tell you about its general tonality, it can be classified as a very neutral experience, with some bias to the brighter and more analytical side of the auditory experience. The bass is excellently reproduced without any unnecessary tweaks that will make the sound artificially enhanced. The midrange is clearly represented without any hitches and weird peaks. It enhanced (without coloration) how instruments and vocals are layered, which is actually the first thing that I noticed when I plugged into this beast upon my unboxing. The treble is where things get slightly different: it makes IEMs/headphones a bit brighter and more technical when used. Every gear that I plugged into it gained an additional level of technical ability and brightness that I appreciated, most especially for warmer sounding IEMs. The only nitpick that I can pick out from using the M15 extensively is its tendency to make the soundstage slightly narrower, resulting in a more intimate listen. This isn’t easily noticeable though, as I have noticed this in my more critical listening sessions with the music that I know by heart.

Overall, the Questyle M15 is truly a monument in dongles, even in my debut experience of it. It’s just too good to be true, especially for people who are into this segment of the hobby. Even for me as a beginner, this is truly a great experience and a more-than-worthy start into the rabbit hole that is the #donglemadness.

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𝙊𝙫𝙚𝙧𝙖𝙡𝙡 𝙑𝙚𝙧𝙙𝙞𝙘𝙩:
𝙋𝙖𝙘𝙠𝙖𝙜𝙞𝙣𝙜 💨💨💨💨🦖
𝘽𝙪𝙞𝙡𝙙 𝙌𝙪𝙖𝙡𝙞𝙩𝙮 💨💨💨💨💨🦖
𝙐𝙄 (𝙐𝙨𝙚𝙧 𝙄𝙣𝙩𝙚𝙧𝙛𝙖𝙘𝙚) 𝙖𝙣𝙙 𝙀𝙖𝙨𝙚 𝙤𝙛 𝙐𝙨𝙚 💨💨💨🦖
𝙎𝙤𝙪𝙣𝙙 💨💨💨💨💨🦖

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GojiFi
GojiFi
@o0genesis0o Thanks for the compliments mate! Goji says hi to you. :D
T
tubbymuc
Love the way the dac looks!

The transparent cover looks good, might be a hassle to daily it. As might break it.
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Questyle
Questyle
@tubbymuc That glass is quite strong, deceptively strong actually. Especially when paired with the leather case, we haven't heard any reports of anyone breaking it yet 😉
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Headphones and Coffee

Previously known as Wretched Stare
Just amazing
Pros: clarity from one end to the other, great extension and low noise on most instances
Cons: some slight beginning noise with certain cellphones, this does dissipate.
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This dongle comes with two cables one is USB-C to C and the other is USB-C to A, the small metal dongle has a clear window to see the internals and lights. the LED are bright, but I didn't find that bothersome. It has both single ended 3.5mm and Balanced 4.4mm for versatility. The M15 also has manual gain adjustment on the side via a sliding switch, LED indicators and as this is written a free case with purchase.

The M15 has very low ground noise, with noise floor of -130dB and its ES9281AC DAC chip is capable of decoding DSD256 native and PCM 32BIT/384kHz as well as an 8X MQA, and very good numbers when it comes to driving power with 22.6mW max on the 4.4mm output and just under 12mW for the 3.5mm output.

Sound impressions:
The M15 is without any doubt one of the best I personally have used. It maintains a neutral presentation with superb clarity and detail retrieval.
The Questyle M15, has both excellent dynamics and superb resolution making it great for critical and fun listening.
Bass, Mids, and Treble present with a linear extension with excellent technicalities.
The soundstage is open, accurate with separation and details.

Afterthoughts:
I used a large variety of in-ear and headphones with this Dongle and it handled them all perfectly.
Fostex T50RP, the HiFiman HE-X4, the Moondrop Blessing2, Kato, and Aria, the Grado SR80x and the Philips X2HR to name a few.

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T
tubbymuc
Thanks for the review! Love the look of the dac.

Slater91

100+ Head-Fier
Transparent indeed
Pros: + Premium materials
+ Great design
+ Removable USB-C cable
+ Balanced output with 4.4 mm jack
+ Neutral and transparent
Cons: - Pricey
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Small, portable DACs with an integrated headphone amplifier are more and more common, with an ever-increasing variety of inputs and outputs. The Questyle M15 keeps things simple while offering some flexibility with a 4.4 mm balanced output as well as a traditional 3.5 mm jack. What really sets this device apart is the design, which is quite unique, but we shouldn’t judge a book from its cover as there’s much more to it than just nice design.

Disclaimer: I received a free unit directly from the people at Questyle, whom I thank. The M15 retails for $249. Buy from Questyle

I originally posted this Questyle M15 review on my blog, Soundphile Review.

Rating: 9/10​

Packaging & Accessories​


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The Questyle M15 comes in a simple yet elegant cardboard box which contains the device itself along with two cables: USB-C to USB-C and USB-C to USB-A. The company kindly sent me an additional USB-C to Lightning cable in a drawstring pouch, which you can buy as an add-on for an additional $20.


Design & Build​


The Questyle M15 has a transparent window taht shows the components



The Questyle M15’s design is surely quite striking. The presence of a transparent window that shows the circuit board with all the components is definitely unusual and shows quite some confidence on the part of Questyle, given how it displays the circuit layout – something that could potentially expose it to criticism from those who are more demanding in this regard. Still, it’s a sight to behold and I applaud this choice as it really sets the M15 apart from the competition. The funny thing about the transparent window is that it allows you to see how Questyle really optimised this device to be as small as possible and there’s no wasted space inside it.


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A more practical consideration about the transparent window is that Questyle took advantage of it to show two LEDs on the board: the on the left hand side indicates gain and is either green (low gain) or red (high gain), while the one on the right hand side lights up to show the resolution of audio being reproduced with green (48 kHz or less), red (more than 48 kHz) and magenta (MQA).

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The Questyle M15 has a flawless assembly, as far as I can see. The main part of the chassis, made of aluminium, fuses perfectly with the glass of the transparent window. The top hosts a USB-C port, while the left hand side hosts the gain selector and the bottom hosts the two audio ports, one 3.5 mm and the other 4.4 mm.

Features & Specs​

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When I first tried out the Questyle M15 it took me a while to understand what was wrong, as the device wouldn’t show up in the available audio devices. Not only that: the system logs (I use Linux) showed that the device wasn’t even being detected as plugged in. It wouldn’t work even with my Android devices. I then realised that the M15 requires headphones to be plugged in in order to show up as an available audio device independently of your operating system, so keep that in mind!

Speaking of operating system support, it is supported by basically every operating system out there and works great with the Steam Deck, too.


Questyle M15


InputUSB (up to 32 bit / 384 kHz PCM, DSD256, MQA)
Suitable headphones impedanceN/A
Output impedance0.4 Ω (single-ended)
0.8 Ω (balanced)
Maximum output power11.97 mW (300 Ω, single-ended)
22.6 mW (300 Ω, balanced)
Frequency response20 – 20,000 Hz (± 0.1 dB)
THD+N (@1 kHz)0.0003%
SNRN/A
CrosstalkN/A



The core of the the Questyle M15 is the ESS Sabre ES9281AC DAC, the same as the older M12. The device uses the company’s own Current Mode Amplification circuits, developed in-house to deliver lots of power while maintaining low output impedance and distortion – as evidenced by the data above. It should be noted that the distortion is incredibly low: at 0.0003%, it is even better than on some desktop devices, which is quite the achievement.

In terms of compatible formats, the M15 is able to play everything but the highest-resolution content, with PCM going as far as 32 bit / 384 kHz and DSD up to DSD256. It is also an MQA-compatible device that effects the final unfold.

Sound​


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I have tested the Questyle M15 with various headphones, including the Sennheiser HD 6XX, the HiFiMAN Edition XS, the Moondrop Stellaris and the RØDE NTH-100.

The Questyle M15 is notable because it delivers a completely black background – there is no hiss or hum whatsoever to be found, even when using a not-exactly-clean USB port (in terms of power, that is).

It has enough power to drive even demanding headphones with good authority; only the ones with very high impedance or extreme current requirements (like some planars) are not driven to their best. In terms of tonality, I find the M15 to be perfectly neutral, with no alterations made to the sound; it sounds really clean and clear, with great representation of the transients that sound fast and well-controlled. Decay is quite short, too, adding to this sensation of speed. Fast headphones like the NTH-100 delivery great transients with the M15 and sound even more engaging. A by-product of this is that there’s also a whole lot of details to be found.

There’s no significant difference in tonality when switching from the single-ended output to the balanced one; the difference is mostly in power output, which means that you should use the balanced output with higher-impedance or more power-hungry headphones (e.g. the Sennheiser HD 6XX) as it’s better able to drive them.

Final Thoughts​


At $249, the Questyle M15 is certainly not cheap. It has, however, everything you might ever need from a portable DAC – and even from a desktop DAC, to tell the truth – in terms of power output and format support. What’s most notable about the M15 is that it offers a completely black background, with no hiss whatsoever even with noisy source devices. This helps it deliver a great amount of detail. It drives even demanding headphones with authority and with sufficient power to make them loud and clear. The overall impression is that of great cleanliness, both in sound and design. This cleanliness has a price, but overall I feel like it is worth the expense, especially considering this is one of the few portable units that offer 4.4 mm balanced output.
o0genesis0o
o0genesis0o
Every where I turn, I see praise of M15 :beyersmile: So tempting

Zerstorer_GOhren

500+ Head-Fier
QUESTYLE M15: The Exemplary Authoritative Miniature Device
Pros: ● A sturdy device with metal casing chassis made of high quality aluminium alloy.
● That window glass panel which you can see the inner workings of its circuitry which is quite fresh and aesthetically eye-pleasing.
● Removable Type-C cable connector.
● Manual gain toggle switch.
● A versatile device supports and compatibility on either software applications level or hardware devices.(Operating Systems and media devices such as PCs, Smartphones, Tablets and Laptops)
● Impressive driving power output for such a tiny device.
● Tremendously uncoloured, unsullied neutral tonality.
● Up to par technical performance.
● High quality 4.4mm TRRS made by Pentaconn.
● 8x unfolding MQA support for Tidal streaming (For MQA listeners)
Cons: ▽ Absence of hardware volume key buttons.
▽ Yearning for at least a tad wider soundstage. (it's just my slight quibbling nature in regards of my concern but I can live with it)
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Your big opportunity may be right where you are now.”

~Napoleon Hill, Author of Think and Grow Rich~


This quote really struck me so much when I received an opportunity to do a product review for an audio company in which I really thought that approaching them is next to impossible. I give my utmost gratitude to my audio mate who really believes in my capability as a decent audio reviewer. He is the one who's facilitating the contact between me and this audio company.

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This audio company that I mentioned is Questyle (as it was already mentioned in the title above). As we all know that the brand Questyle especially to the veteran audio enthusiasts that it is a boutique audio company which has a cult following among the audio community. The brand Questyle embodies excellence in product quality and the delivery of the best possible sound quality that an ardent audiophile can derive upon.

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Questyle is a Chinese premium boutique audio company whose product range mostly offers desktop amplifiers and other mobile audio solutions such as USB DAC dongles and digital audio player. It was founded in 2012 in Shenzhen by some visionary individual who wants to deliver the best audio experience with proprietary patented technologies such as CMA (Current Mode Amplification) and a 5Ghz wireless lossless audio system in a mobile and desktop-grade in a very compact form.

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I'm familiar with Questyle since 2018 as their DAP, The QPR1 was a stuff of legend among the audiophiles in the audio community scene. Some even claimed that they finally found their "Holy Grail" which really even piques my interest about them even further. That's why when Questyle contacted me if I could do a review on their product, I eagerly accepted their offer without hesitation.

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This is Questyle M15, It is their latest flagship headphone amp dongle which has a removable type-C connector with two types for termination jack of different power output. It is made of CNC milled aluminium alloy and has a size dimensions of 16.8mm x 27.2mm x 12mm and it is of a rectangular shape just like most typical USB DAC dongles of the same form factor. At the top of the panel, it has clear tempered glass where you can see the internals of the M15 which is quite fascinating and eye-pleasing where you can see the circuit board with its internal components like DACs, microchips, headphone jack casing, USB type-C jack casemate and their patented CMA with its transistors which I will explain later. At the both ends of this device, this is where the different types of ports situated on both opposing side, the USB type-C port on the other side and two types of termination jack, one is a 3.5mm TRS and the other one is a 4.4mm which was manufactured by Pentaconn, a Japanese brand that makes high quality audio components to other midrange and high end Hi-Fi brands like Sennheiser and Sony. At the one side of the parallel part of Questyle M15, there lies a toggle switch for adjusting the gain output manually where you can check the colour- coded status in a glass panel via its light indicator.

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GREEN LED LIGHT = LOW GAIN MODE

RED LED LIGHT = HIGH GAIN MODE

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Furthermore for decoding sampling bitrate, there is also a dedicated LED light which is also placed at the opposite side with the gain light indicator. Questyle M15 can support PCM lossless format like FLAC, WAV and ALAC up to 32-bit/ 384KHz and DSD format up to DSD256(native). MQA decoding via streaming services like Tidal is also supported and can unfold up to 8x via hardware decoder processing renderer of its DAC.


DATA GREEN LED LIGHT - 16-32 bit, 44.1 KHz - 48 KHz.

DATA RED LED LIGHT - 16-32 bit bit, 88.2 KHz - 384 KHz / DSD 64, 128 and 256.

DATA MAGENTA LED LIGHT - MQA decoding and unfolding (works only in Tidal)

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Other component parts of the Questyle M15 are the DAC, Amplifier and a power management module which I will divide it into parts.


ES9281AC is Questyle M15's internal DAC chip. It is ESS' latest flagship DAC which is mainly used for USB DAC and other mobile applications to achieve a processing and decoding execution similar to some desktop grade DACs. It also has a built-in high performance SABRE amp to achieve up to 2 Vrms output. There is also a jack detector on it that serves as "impedance sensing" to regulate a power output to load with proper resistance value to avoid unwanted erroneous reading due to external sources such as moisture and dirt.


CMA (Current Mode Amplification) is Questyle's proprietary patented technology crown jewel. It is a System-in-Package module which has multiple "audio amplification engines" with unified parts of circuits, chips and transistors in a single enclosure of a package to deliver an accurate, excellent detail retrieval and ample dynamics for a high quality sound reproduction either from a studio or recorded live performances. With its transistors and advanced circuitry to regulate voltage output and amplification, it manages to achieve a performance peak similar to a Class A amplifier (you read it right, an almost Class A amplification performance). There are two CMA modules that are implemented in the M15 dongle. You can check more infos about the CMA technology HERE for more technical description.


For its power supply module, It uses an analogue IC voltage regulator from Torex Semiconductor which is a Japanese firm that has years of experience in IC manufacturing and with extensive R&D to provide a better power efficiency and regulates well the temperature inside of the Questyle M15 to avoid overheating.

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Questyle M15 packaging is quite simple when it comes to inclusions but still looks premium and elegant in presentation on how its contents inside are properly stacked in order.


Here are the included accessories inside of the Questyle M15's packaging box:


■ Questyle M15 USB dongle.

■ Short USB Type-A to USB Type-C cable.

■ Short USB Type-C to USB Type-C OTG cable.

■ Basic instruction manual.

■ Warranty card.

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Bonus: Questyle also included an M15  Leather Case in green colour.

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Like all USB DAC/Amp dongles, M15 is also a plug-and-play device with its handshake protocol to bypass any devices' stock audio resampling system by using a specific apps (for Android OS), streaming apps setting options (Tidal, Apple Music and Amazon Music) and Desktop OS settings (Mac OS, Windows and Linux). With a plethora of supporting devices like Android smartphones, Laptops, Personal Computers, Tablets (Android and iOS) and DAPs, Questyle M15 is indeed a very versatile tool for a mobile hi-fi tool.

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If you are an iPhone user, you need a Lightning to Type-C cable which can be purchased from Questyle's official site.


Here are some information regarding the prerequisites on recommended versions of major operating systems and required apps for supporting playback for M15 in Android.


Android OS - you need at least a 5.0 version up to the latest one. The music apps that support Questyle M15 dongle are UAPP (USB Audio Player PRO), Hiby Music Player, Neutron App and Onkyo HF Player.


Windows OS - at least Windows 10 version 8.13 with no additional driver installation.


Apple MacOS - works mostly in all versions without any additional driver installation requirement in the system.


Linux OS - like MacOS, it works pretty well in all distros like Ubuntu, Debian and Linux Mint without any necessary driver installation requirements.


iOS/iPadOS - latest OS version that supports Apple Music app in lossless mode.



Regarding its power output delivery, Questyle M15 currently has the strongest power output in my current collection and some USB DAC/Amp dongles that I've tested in the past. Planars IEMs can be driven properly without breaking a sweat with impressive results. So harder-to-drive cans and some power demanding IEMs will be amplified properly. Even on some super sensitives, low impedance finicky IEMs, there is no hissing nor scratching sound present within its sonic background.

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Here are more technical specification in power output rating on both audio jacks (Datas are provided by Questyle)


● 3.5mm TRS/SE= 300 ohms, Po= 11.97mW

VDF=1.895 Vrms, THD+N= 0.0045%


● 4.4mm TRRS/Balanced= 300 Ohms, Po= 22.60 mW

VDF= 2.624 Vrms, THD+N= 0.00057%


Due to the absence of hardware volume key buttons on M15. Adjusting its volume level will be done via volume key buttons or knobs of devices sources. Android music apps that supports USB DAC dongle has better volume steps with gradual incremental gain while adjusting the volume amount based on your preferred listening level.

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Another reminder that Questyle M15 doesn't have a built-in battery and it acts like a parasitical implement with its host device's core power source to syphons off some amount of power to amplify the head/earphones. Due to the Torex power management system tech, Questyle M15 power extraction on its device host is well-regulated and its draining power is somewhat minimal with efficiency. So it is advisable to have a mobile device that at least has a high capacity battery for a longer usage to act as host for this implement.

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As for tonality aspect, Questyle M15 has a balanced-neutral tuning with very clean, flawless, organic, sufficiently crisp with high degree of resolving yield. This is one of the most uncoloured sounding devices that I've encountered to a greater degree.

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LOWS/BASS:


When it comes to bass quality, it is very clean, articulate and very responsive with adequate texture in both parts of the bass region.

Sub bass has excellent depth reach as I discerningly felt those rumbling sound. Listening on sub bass focus tracks from some genres like Hip-hop, RnB and Synth-pop has a very detailed reverberation produced by low tuned bass guitar, synthesizers and some electric drums.


Mid bass has an ample texture to give a body on these specific instruments like bass trumpets, bass guitars and bass drum kicks. Bass trumpets has this realistic tone as sound very intense, warm and full sounding just Ive listen to orchestras and military parades, bass guitar has a very topping quality that its growls have these crunchy dark, heavy and very resonant and even slapping, fretless and other type on picking on every strand is even well-detailed. And the bass kicks are very authoritative that exudes being thunderous and pounding one as the bass kick drum sounds like that as realistic as possible. (I usually attend on some underground musical gigs from Metal to Skas)


Bass-Baritone vocals have even garnered my attention on how it is presented in a guttural and strong manner. This bass quality should be presented in a very organic way, not too boomy nor too lean sounding.




MIDRANGE:


Unequivocally, this is a very impressive and awe-inspiring midrange quality. Pristine, neutral and translucent that I even sense those layering elements of instruments and vocals. (I'll explain later in the layering aspect on technicalities part of this review).


Male vocals has an ample texture that gives a definition of being cohesive to all vocal types and ranges from a guttural bass voice to stately tenor vocals with its brassy and dazzling nature (love to hear those Three Tenors vocals especially Pavarotti). As for female vocals it has this sense of being organic, clean, very detailed, rangy and energetic. I'm a midcentric type of listener so I want my female vocals to be articulate, delineated and dynamically vivid. To describe the qualities of female vocals, I can enumerate in many possible descriptions. angelic, euphonic, luscious, well-modulated and sensuous that it really pleases my hearing senses in a very captivating and pleasant manner. All these descriptive characteristics exhibited in all female vocal ranges from a soulfully and sombre contralto to a vibrant and vigorous sopranos.


All types instruments ranging from percussives to strings have very natural and life-like sounding in a very engaging not to sound exaggerated and inaccurate tone that most coloured sounding usually exhibits as M15 maintain to sound uncoloured and equitable as possible. On percussive side, tom drums have this hard and majestic sound every hit by a drumstick, snare drums sound very precise, sharp and penetrating that its rhythmic attack is well-appreciated with accuracy. While timpani has this dull,dry and velvety sound depending on how it will be executed in different note ranges. As for strings instruments, it is so detailed that I clearly hear every pluck in each string of a guitar (Tears in Heaven live by Eric Clapton) and surprisingly, if you are aware the different tonal attributes of a guitar (acoustic) and very familiar with its choice of material usually types of wood that affects the guitar's overall tonality, you will notice the different tuning of it either it is warm sounding, balanced, dark, meaty or crisp. Violins have these different sound characteristics like lively, brilliant, rough or austere as it depends on the quality of construction and tuning of it. Brass and woodwinds are depicted in a natural and realistic manner that trumpets has that metallic and brilliant sounding, Horns has this muffled and velvety sound, Flute and fife has this bright, whistling with a sense of airiness and lastly, the sound of clarinet has these characteristic of lustrous and lively sounding.


It's too long to elaborate on how the midrange quality of Questyle M15 is beautifully well-rendered, and that it is very accurate, has an excellent detail restoration with greater degree of resolving without some colouration.



HIGHS/TREBLE:


As a neutral sounding DAC/Amp, Questyle M15 exceeded my expectation of the quality of treble. It is very natural and inoffensive, neither too smooth nor aggressive in presentation. I contentiously believe that this is the truest representation of treble quality. Exceptionally detailed, with just a sufficient amount of shimmer not too make it more brighter and very airy with lots of harmonics.


Cymbals' sounds are precisely depicted in an instinctive manner as their sounds are very metallic, glistening, brilliant and sizzling. Hi-hats has this raw sound that it portrays its innate sound to have this shortened sizzle and buzzing characteristic.


Of all these impressive feats of Questyle M15 on how the treble quality was tuned. It managed to balance out and even improved those inherent character weaknesses of both aggressive and dull, dark tuned treble.




GENERAL TECHNICALITIES:


As highly resolving DAC/Amp mobile Hi-Fi dongle with the highest degree of superb technical performances, Questyle M15 is a highly capable that it has a good gap and spacing of all the elements inside of a track with a very orderly placement of every distinction of dynamic and frequency layering with in a clear, pitch-black sonic canvas. Imaging is very perfectly executed as I clearly locate the placements of vocal(s) and instrument with no sense of haziness and obstruction in a 3D-like sense of immersion.


Regarding its soundstage proportion, its width dimension is fairly more of an above average, with excellent height and a well-defined placement between front and rear as it does have less reverberation with just sufficient amount of projecting energetic streak to have that sense of immersion and envelopment. Despite of that above average soundstage, it does have a spacious head stage within its perceived spatial field.


As for tonal colour, Questyle M15 is certainly neutral with almost to none amount of colouration. And with its exceptional resolving on detail retrieval on both micro-details and macro-dynamics and superb clarity, Questyle M15 is a fine piece for audio reviewers, audio professionals and audiophiles alike that a terribly produced and defectively mixed track will be thoroughly dissected to expose its flaws from sonic artefacts to audio clippings.




PEER COMPARISON:


AudioQuest Dragonfly Cobalt (£258/US$300)


● Currently, the most expensive USB DAC Dongle that I have tested until now. Cobalt has a smaller form factor compared to Questyle M15 and it has hardware volume control button which is a more logical and more convenient implementation. But there are some caveats on Cobalt, it has only one single jack output and it is a 3.5mm SE and it is certainly designed for PC or laptop usage as it has a USB-A as its main connector which if you are a smartphone user, you really need some adapters which add more complexity and hassle.



● Regarding its tonality, Cobalt has a tad of colouration with its overall frequency range spectrum compared to M15 which is more neutral and organic sounding but Cobalt has still a clean and clear delivery. Different tuning for different folks, which you will choose? A warmer and musical Cobalt or an unadulterated and a bit clinical tonality of M15?



● On paper, Cobalt has limited playback resolution as it was only capped up to 24-bit/96KHz but it has Tidal MQA playback support. Both Cobalt and M15 has ESS DAC on their internals but different model, Cobalt uses a popular and reputable ES9308Q2M on its system and microcontroller power management chip from Microchip Technology Incorporated which is also a reputable company (they even have manufacturing plant here in my country). Cobalt has a bit wider soundstage but M15 has better imaging, separation, layering and resolution capability. Cobalt's power output is a bit underwhelming compare to M15.



LOTOO PAW S1 (£146/US$169)


● I've tested this one a few years ago from a friend, Paw S1 has also a solid built device like M15 and it's also made of metal alloy and if my memory serves right it's a bit more weighty compared to M15. It also noted that it has a small LED display to check the volume level and EQ mode…Yes, it has a volume control button and EQ system. PAW S1 uses a DAC chip from highly regarded audio solution maker, Asahi Kasei with its AKM4377 model.


● As for tonality, S1 is more coloured sounding due to added warmth but it has a velvety and luscious midrange in which AKM DAC is known for with its Velvet Sound tech. I can safely say that Lotoo PAW S1 is more for fun sounding and pleasurable musical tuning rather than for critical listening.


● It has lesser power output compared to M15 in both 3.5mm and 4.4mm but good enough for IEMs and earbuds. Most technical aspects are a bit inferior on S1 but at least it has a wider soundstage and even more spacious headspace.



As I end my review and put a verdict on this one, All I can say is that Questyle M15 is an absolutely outstanding mobile device in another higher-tier category. It has tremendous sonic quality performance and top-notch technical performance which only rivals some desktop-grade DAC/Amps in midrange and even some top-of-the-line Hi-Fi range ones in my humble opinion. (Still desktop DAC/Amps and Preamps has many functionalities and has a proper amplification within its circuitry to handle high powered and demanding speakers and headphones).



And now regarding the tale that I've mentioned a while ago about the "Holy Grail" thing on a Questyle DAP. Looks like that I finally have an enlightenment on how great Questyle products are, and my scepticism on that man's claim seems to be eroded and shattered and I became a true believer in Questyle (I'm an irreligious bloke though). Once again, Questyle M15 delivers a truly marvellous neutral tonality and a life-like timbre with a highly-resolving and terrific technical performance that truly Questyle will be proud of their prowess and elan in audio engineering.


Questyle M15 is currently available to all online stores in popular e-commerce platforms. If you are really interested in purchasing this device, you can order them directly from Questyle in the link below this description.


☞●QUESTYLE OFFICIAL STORE●☜

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Some Tracks Tested: ( * = 16-bit FLAC, ** = 24-bit FLAC, *'* = MQA, '*' = DSD, *'= .WAV)

Alison Krauss -When You Say Nothing At All *
Jade Wiedlin - Blue Kiss**
Led Zeppelin - When The Levee Breaks **
Mountain - Mississippi Queen *
Queen - Killer Queen **
Guns N' Roses - Patience *'*
Eric Clapton - Tears in Heaven '*'
Sergio Mendes- Never Gonna Let You Go '*'
Pearl Jam - Daughter **
Roselia - Hidamari Rhodonite *
Assassin - Fight (To Stop The Tyranny)*
Celtic Frost- Visual Aggression *
New Order - Blue Monday *
The Corrs- What Can I do (unplugged version) *
Jimi Hendrix Experience - Voodoo Child *
The Madness- Buggy Trousers *
Metallica - Motorbreath **
Mariah Carey- Always Be My Baby *
Destiny's Child - Say My Name *
Malice Mizer- Au Revoir *
Mozart - Lacrimosa *
New York Philharmonic Orchestra - Dvorak- Symphony 9 " From the New World." *
Eva Cassidy - Fields of Gold (Sting cover)*
Michael Jackson - Give In To Me *
Exciter - Violence and Force *
Diana Krall - Stop This World **
Debbie Gibson - Foolish Beat *'*
The Sisters of Mercy – Lucretia My Reflection**
Suzanne Vega – Luka **
Lauren Christy – Steep *

P.S.
I am not affiliated to QUESTYLE nor receive monetary incentives and financial gains as they provide me a review unit for an exchange of factual and sincere feedback from yours truly.

Once again, I would like to thank to Mr. Zach of QUESTYLE for providing this review unit. I truly appreciate their generosity towards me and other reviewers.

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Zerstorer_GOhren
o0genesis0o
o0genesis0o
Great review, mate! It seems that every where I look, I see praise for M15. When I reviewed the S9 Pro recently, I couldn’t give it more than 4/5 because the spectre of M15 is always on the horizon. It seems M15 is not as draining as S9 Pro :thinking:

Will try to grab one to review one day, after upgrading my top IEM (likely forever, because I keep buying cheaper new stuffs for review:beyersmile:)
Zerstorer_GOhren
Zerstorer_GOhren
@o0genesis0o thanks mate. I'm glad that you are enjoy reading my content.

Voxata

Headphoneus Supremus
Questyle M15 - Proving Questyle is back
Pros: Sound quality, size, efficiency, power, staging/layering
Cons: Gain switch difficult to access when inside of the case, can be a good thing though for no pocket sound surprises.
Questyle M15 - This review is going to be a stream of thoughts and impressions. I hope you enjoy.

Today on my desk I've got the Questyle M15. The M15 at this point has a strong following and I've been determined to see if that following would stand up past the initial release hype. Questyle has promised a full CMA implementation in this tiny dongle with power consumption and running temps that are in check - we'll see if they have held up to that goal in this review.

Before receiving the device I did what any sane person would do - research and assume, right? On their website Questyle has marketed this as having incredibly low distortion, to the tune of 0.000X% and beyond. Inside is a capable ES9281Pro DAC chip that hands off the signal to their new current mode amplification SiP modules. I'll be honest I'm a bit in the middle on if I'm a fan of Sabre. I have heard DACs flat as a board with enough pierce in the treble to give me a headache before the first song is over. The Fifteen from Questyle is the first later revision Sabre chipset I've heard that has completely transformed my impressions of Sabre largely thanks to the CMA output stage.

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Given this experience, I had high hopes for the M15. I was a bit worried when I read the power specs however. For some reason it is measured on their site at 300ohms. The M15 supposedly puts out 11.97mW on the 3.5mm output and 22.60mW on 4.4mm. Once I received the dongle in though I believe numbers are so incredibly conservative it isn't even funny. With my AKG K712 I am sitting at 23 OS volume in low gain with Foobar playing at -18dB attenuation. This is my upper threshold of what I can handle for routine listening. This dongle is an absolute powerhouse. Switching over to my modded HD650 I could only nudge Foobar to -16dB! This performance proved the M15 is more than capable of driving anything I own, either IEM or full size power hungry headphones.

When listening to the M15 and switching to IEMs one has to be careful. I dropped the volume to the floor when switching over to IEMs and creeped up from there. It seemed that from my phone the power was a touch more conservative (still plenty of it though) and my PC was capable of feeding it even more. So, this gives me confidence Questyle has power management in check on this little device.

Also very important to note is that the running temperatures on the M15 are crazy good. It barely gets warm to the touch, even attached to my desktop PC. The new CMA SiP modules are an engineering feat to have such power. Very akin to THX design however sans the sterility in sound, but more on that later. In my pocket the M15 was completely unnoticeable. Questyle was on a mission with this dongle I believe. Size, power, sound and efficiency. The size to me makes the lack of internal battery or wireless connectivity a non issue. The sound from the M15 blows every wireless device I've ever tried out of the water, enough to sate my old school belief of 'wired of always better' anyways.

My mobile testing consisted of my trusty OnePlus 7T and as a mobile platform the M15 exceeded my expectations. I had no dropouts, stuttering or sync issues. I also did not encounter any EMI noise - which given that one side is glass I suspected the M15 may have been impacted. No issues, though given it is a dongle I'd have rather had the choice to either have a removable metal plate over the glass or just not a glass side at all. It has taken a few good thwacks in my pocket though, so whatever they are using is rather robust. There is a nice leather case for it available through Questyle as well in several colors. It does allow for some nice visibility through the glass of the status lights within. These notify you of different rates and connectivity/power. Let's move on.

(The size of the M15 is incredible)

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I figured I'd just use the M15 as a convenient portable for LAN events and on the go. Definitely for downtime at work. The M15 has proven to me that it can fulfill those roles, however it went a step further. It completely replaced my desktop setup for gaming. The M15 is accurate, incredibly so. When testing with Hunt: Showdown which features binaural audio I was greeted with a boundless soundstage with excellent layering. Bass was in check yet present and engaging. Treble was not so explosive that it was uncomfortable and the midrange is so smooth without losing detail. It is also very clear. Even better though, it was resolving beyond even some of my desktop gear. Decay is incredibly detailed and natural so the sound doesn't come off as either too warm nor too sterile. The negative feedback gear I've owned previously (think THX, Topping, etc) has a habit of squashing the sound and compressing the stage with a very 'wall of sound' effect in this game. This capability was very unexpected from the M15.

When it comes to music the M15 performed incredibly well here as well. I've got some state of the art desktop gear and for a dongle not to embarrass itself in the slightest is a huge testament to the engineering that went into it. With my setups each has a specific pairing it excels at. The Fifteen dominates with my AKG K712/HD660S with the BF2/J2 coming through with a different flavor for these headphones. LIM/Rag2 lights up my Sennheisers and my LS50 speakers. Mixed up, each of these systems looses their engaging synergy and in case of the AKG K712/LIM/Rag2 setup becomes harsh. With the M15 I experienced an enjoyable listen through everything I connected to it. Was it on the level of Schiit gear with an HD650? No.. Was it a lesser match like other pairings I've got? Not at all. Same can be said when arranged the other way. When listening to the M15 for extended periods I didn't outright miss my other desktop gear, which is the highest praise I've given any portable.

As far as putting a pin on the sound I'd call it detailed yet natural. The resolving capability from this DAC puts it well ahead of any competing gear in the same price range. A competing Schiit stack would have to be over the 1K mark and still doesn't perform as admirable with every headphone/IEM I've thrown at it. When a key pairing hits it can absolutely be better, but the M15 itself doesn't seem to care what you connect to it. Everything sounds great. The Bass performance from the M15 goes deep and is very engaging. It takes the HD650 as low as it will go and the AKG K712 even further with a strong but not overwhelming presence. It is also fleshed out. Male vocals are engaging with have weight and authority. Midrange is incredibly resolved and the treble has sparkle that doesn't overwhelm. There is no thin sound from this dongle, which cannot be said for much of the competition I've heard (here is to looking at you, FiiO...sorry)

There is one gripe I do have about this device though, and that is when connected to a PC that gets turned off I needed to unplug and replug the headphone cable to get the M15 to 'wake up' and be seen again. I'm assuming this could be altered in the firmware, I'm using Windows 11. It could also be a standby power setting on my system that is causing this and it isn't a huge deal. I don't think it was designed to be a desktop device at all yet it really is competing in that realm. With these new modules I really hope Questyle puts out a USB powered desktop Dac/Amp. There would absolutely be no competition in this segment if the performance exceeds the M15.

As far as portable comparisons I can comfortably say the M15 has outperformed everything I've heard and owned. It is more layered than the iDSD Gryphon - and somehow more usably powerful despite the Gryphon's specs. The Gryphon had some compression in the lower registers that put me off. Where the Gryphon exceeds the M15 is capability of features and compatibility. FiiO BTR series? Not even close when it comes to sound quality however it IS wireless. iDSD BL/Signature? Not neutral in any sense of the word but I would say the bass is more engaging, given it's added coloration. The Sig/BL soundstage has a three blob thing going on and it definitely lacks the M15's resolving capabilities. I struggle to point out a specific weakness with the M15 while it puts a performance in each metric that could be considered solidly very good.

I've not much else to add on the M15, aside from that the praise it has received since launch is absolutely warranted. Many of these have sold and the thread is active, yet I've not seen many used units for sale. I'm observant of these things as it sends up a possible flag of hype in my hunt for great audio. Anyways, thanks for sticking around for this long and I wish all my readers the best. Jam on!
White Hat Bob
White Hat Bob
I have the BTR7. I have compared the Earmen Collibri, which has the same ES9281Pro and ESS SABRE PRO chips as the M15, with the BTR7, which has the ES9219C and THXAAA-28 chips, and the Collibri definitely sounds better than the BTR7, so it's safe to assume the M15 will also likely sound better than the BTR7. The BTR7 has a nice implementation of a mini-screen, Bluetooth, nascent EQ, a connected app. etc, but the sound is meh, especially when using Bluetooth. The Collibri has none of that but has a great case (with a belt clip which the BTR7 case does not have), separate USB-C and Data ports (which help it sound so good), a 5-hour battery, and a button/case/balanced 4.4 mm pentaconn configuration with strong output that is great for walking/running. If I didn't already have the Collibri, I'd definitely take the M15 over the BTR7 even though I'm a FiiO fan (Love my FiiO M11 Plus ESS DAP).
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Voxata
Voxata
Thanks for this info White Hat! I'm not a huge fan of the THX sound on mobile devices I've tried. I think the Questyle amp circuit used here has a ton to offer. I hope you get to try the M15, it is priced really well for the performance.
corgifall
corgifall
Great review!!
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gadgetgod

1000+ Head-Fier
Questyle M15 Portable DAC/AMP Review: Robust Build, Solid Looks, Impressive Sound!!
Pros: Eye candy, the transparent front looks super good.
Impressive sound, fluent dynamics, transparent, clean signature.
Synergizes well with almost everything I tested it with.
No background hiss or noise issues with sensitive IEMs.
Cons: No physical volume keys, depends on the connected source for volume adjustment.
EMI Noise when source uses Mobile Network. No issues while using Wifi.
Hello Friends, Today, I am going to share my review of the king of the dongles, the @Questyle M15. Questyle Audio Engineering is a premium HiFi audio gear brand from China that specialize in designing Desktop and portable DAC/AMP solution. They cater to the premium consumer with their class-leading range of HiFi audio gears with famous models such as CMA Twelve, CMA Fifteen, QP2R, QPM, etc. Quite recently, Questyle entered the budget market with their range of Portable DAC/AMPs, mainly with the M12 and the M15. M12 is the budget model while the M15 is the flagship model that comes with ES9281AC premium Sabre DAC and Questyle’s patented CMA(Current Mode Amplification) SiP Modules with a total of four CMA Amp Engines. Well, I have spent the last few weeks with the M15 by my side(About 6-8 weeks), and now I feel I have spent enough time with the device to give my impressions on the same. Let’s begin with the unboxing part but a little disclaimer first.

A short Disclaimer:-

I received the M15 courtesy of Questyle, I just had to pay the custom duty that was charged in my country on the package. Be assured, all the impressions and opinions in this review are completely my own and are based on my own subjective understanding of the HiFi audio world. I would like to thank Questyle for giving me this opportunity!! You can check out the technical details and purchase it from the Hifigo link below(non-affiliated):-

https://hifigo.com/products/qustyle-m15

You can also read my review on the Gizaudio website here.
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Let’s Get Done With The Unboxing:-

M15 is a portable device and it comes in a compact box. It’s a plain black colored cardboard box that has a minimalistic design approach. You have the Questyle and M15 branding on the front and some basic information on the backside. The package opens in a sliding manner, where you pull out the internal box from the outer casing. Inside we have the M15 sitting firmly into a hard foam cutout layer. There’s a USB Type-C to Type-C connector cable and a Type-C to Standard USB Type-A connector cable right underneath our M15. Apart from this, we have a user guide booklet and a warranty card. That’s all about the main package. I also received a small box carrying the leather case of the M15. It is available to purchase separately.

Package contents:-

>M15 portable DAC/AMP.

>USB Type-C to Type-C cable.

>USB Type-C to Type-A cable.

>Warranty card.

>User guide.

>Leather case(To be purchased separately).
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Design & Build:-

During my journey as an audio enthusiast I have had a small share of experience with some portable DAC/AMPs from different brands like iBasso(DC03), HiBy(FC5), xDuoo(Link 2 Bal), Shanling(UA3), etc, IMO M15 trumps them all with its outstanding build and form factor. Please don’t get me wrong, none of the ones I mentioned above have a bad form factor or bad build quality, they all look super good in their own place, but the M15, it looks spectacular, literally a candy to the eye. The device has a metallic chassis with a glass front. The entire front panel is made up of durable glass through which the entire internal arrangement is beautifully visible. You can see each and every single chip inside easily. M15 has two small Leds near the USB connector, one that indicated Data input(this glows green for standard signal and red for Hi-Res lossless signal quality/MQA signals), and the second is the gain LED that glows in green for the low-gain and Red for the high-gain mode.
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In the Images M15 looks huge compared to the other DAC/AMPs, It’s a little bit bigger than the other similar devices in the market but not huge or bulky by any means. M15 houses two headphone output ports, one single-ended 3.5mm and another balanced 4.4mm. It feels super good to hold as Queasily has treated it with a rich matte finish. There’s a switch on the side that allows for gain change, but no physical keys for volume adjustment. Overall, Super impressed with the build and design of the M15.

IEMs & HPs I have tested with M15:-

During my usage period over the past few weeks, I have given a good amount of IEMs to the M15. I tested it with IEMs from every range, be it the entry-level CCA CRA or the flagship 64audio Tia Fourth. Questlye’s patented CMA technology makes the compact M15, a powerful device. It was able to drive my ZMF Auteur to about 80% of its capabilities. M15 synergized well with almost everything that I had given it, here are some short notes on my favorite pairings.
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Sennheiser IE600+Questyle M15:-

Absolute bliss, the M15 and IE600 synergize so well together. M15 brings the true capabilities of IE600 out with its transparent and smooth sound presentation. This is my primary go-to setup for regular music listening on my iPad(Apple Music), and watching some Netflix, and YouTube.

64audio U12T and Tia Fourte+Questyle M15:-

Out of all the sources that I have currently, be it the Shanling M7, be it the Shanling UA3, or be it the Astell&Kern Kann Max, M15 has the best tonal balance with the 64audio IEMs. Please don’t get me wrong, obviously, dynamics were produced better on the M7 and the Kann Max, but tonally speaking, M15 doesn’t lack behind by any means. It allows the U12T and Tia Fourte to breathe properly and produce a legendary experience with every single track.

LETSHUOER D13+Questyle M15:-

Regular companions for my casual music and Youtube sessions on my iPad. With the M15, D13 shows its true, powerful bass response and still maintains good clarity in the other regions as well. Pretty good combo for all-time use.
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Apart from these above-mentioned IEMs, I have also used M15 with BQEYZ Topaz, LETSHUOER S12, Campfire Audio Solaris OG, Softears RSV, and a few more sets. No complaints with any combinations, heck M15 turned out to be a perfect match for most of the IEMs I have tested it with.

Sound Performance:-

How do I expect my sources to sound? IMO they should synergize well with my IEMs(that the M15 does), they should have a transparent, clean sound that brings the true performance of my IEMs/HPs out. Well, to my pleasure, this is how the Questyle M15 actually sounds. This little baby here has got a transparent sound signature with low distortion and clean, noise-free background in the output signal. Even with sensitive sets like the U12t, Solaris, and LETSHUOER D13, the M15 maintains its clean presentation. I don’t find M15 to boost any of the frequencies unnecessarily or take the life out of any frequency region, rather it retrieves most details and dynamics from my music.

Tonally speaking, Questyle M15 gives a smooth, rich tone to its output. Dynamics like note-definition, staging, layering, and imaging, are reproduced beautifully with the M15. Let’s discuss a little about different frequency segments separately.
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Lower-End/Bass Response:-

M15 presents a clean and precise lower end. It doesn’t overly exaggerate the bass response for any given set. For sets such as Letshuoer S12 and Sennheiser IE600 which have a powerful bass response, I find them to have a controlled presentation in the bass region with the M15. With the IE600, the bass response is very well-refined, mid-bass slams are nicely textured, and the sub-bass rumble is deep and thunderous. M15 allows items to go deep in the lower end and deliver quality extensions.

Mid-range:-

M15 greets the listeners with a lovely midrange. It’s spacious, airy, and has a clean texture. Vocals sound phenomenal, both the male and female vocals convey emotion with their well-textured clean presentation. M15 maintains a good balance between lower mids and upper-mids. You won’t notice vocals getting shouty even at louder volumes on vocal-focused tracks or instruments losing details in any given genre.

High-Frequencies/Treble:-

Questyle maintains its sweet response in the high-registers too. I don’t notice any of my IEMs going harsh or fatiguing even at loud volumes. There’s no noticeable sibilance or harshness with the m15 as a source, in fact, high notes of vocals and instruments are produced beautifully with good resolution and clarity. For any portable DAC/AMP, I would say Questyle M15 does a great job with its crisp resolution and sweet tone throughout the frequency band.

Dynamics:-

Of all the Portable DAC/AMPs that I have tried to date, the Questyle M15 seems to have the best dynamics so far. I won’t mind saying that it beats some mid-fi DAPs easily when it purely comes to dynamics like soundstage, imaging, layering, and separation. While I agree this also depends on how capable the IEMs are, but M15 brings life to almost every single set that I have given the M15 to.
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A Few Things That Can Be Improved:-

Basically, sound wise the Questyle M15 fits perfectly for my requirements. It has a dynamic, lively sound and usually synergizes well with almost everything I have given this beautiful DAC/AMP. But there are a few things that could be improved with the M15.

Firstly, there are no physical volume control buttons. Basically, there’s no volume control through the DAC, one always has to adjust the volume through the connected source. While it is not a big deal, three to four times I forgot to adjust the volume on my source, and it was set at full for the USB output. So basically, my ears had a stroke for a short while lol.

Secondly, M15 introduces some noise when we use it with smartphones/tablets with cellular network streaming. I personally don’t use Cellular streaming as I am mostly near a WiFi connection, but some people faced this and we had a discussion on the Head-Fi forum for the same. There’s no such issue when using Wi-Fi, but with streaming on a cellular network, there’s Noise interference.

Apart from these two points, I can’t think of any other issue with the M15.
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Short Comparison Against xDuoo Link2 Bal:-

Link2 Bal is a highly-capable DAC/AMP from xDuoo. It delivers a punchy sound performance that brings life to most of my transducers. It is very much comparable to the Questyle M15 in its presentation but I would say M15 takes the things up a notch when it comes to dynamics. M15 shows better staging with a tad bit better airiness on the stage. It feels more spacious to my ears. Bass feels tighter and more controlled on the M15, Link2 Bal isn’t very far, it’s just M15 has a better presentation in comparison. Midrange shows more air and clarity on the M15 and treble has a smoother response. Please don’t get any bad ideas for the Link2 Bal. It’s a pretty amazing DAC/AMP too, but the M15 is just a step ahead in every possible way.
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Final Words:-

I am more of a Portable Player guy, but often I have given time to portable DAC/AMPs. Nothing so far had me hooked on them for my day-to-day usage. The Questyle with its impressive performance gets a special place in my heart. I absolutely adore the impressive sound performance of the M15, it sounds phenomenal throughout the frequency band. Not to mention, the transparent glass front panel adds 100 points to its great design and looks!! Well, that’s about the Questyle M15 from my end, I would like to thank Questyle for this opportunity!!

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SinghGaurav007
Nice and detailed review
NymPHONOmaniac
NymPHONOmaniac
Love this M15!
gadgetgod
gadgetgod

SifatBD

New Head-Fier
Questlye M15 - The Alrounder
Pros: Natural Sounding
Excellent Upscale grading
Driving Power is huge
True MQA decoding
Compact Size/Light Weight
Fabolus looking
Gain Switch
Bang for buck
Cons: Glass Panel, Can be broken if not carefull
Absent of Volume Button
High Pitch on some songs
Treble
Dongle has now become a must have auxiliary product for anyone which helps a lot to get better output from even a phone. Sometimes it may not be possible to buy or carry an external big size amp/dac or dap when you are travelling
Dongle has made that easy. From the beginning of the release the m15 has attracted so many people that i also wished to check it out

Previously I have used dongles but those were not as pricey as this one. So I was a little bit worried about whether it would be able to give me performances according to its price . The price was about 250$. But later I got relaxed after experiencing the Questyle M15
There was another dongle m12 from the same company at half of it's (M15) price which was also a good dongle as far as I am oncerned.Yeah I cannot afford all the dongles but i always keeps updates from local friends and colleagues.

Specification:

OPERATING SYSTEM REQUIRED
Android phone and pad: Android 5.0 and above
PC: Win10 1803 and above
Apple cellphone: iOS (You need to buy an OTG cable for Lightning to Type-C.)
Apple computer: mac OS

DAC CAPABILITY
PCM: PCM: 32kHz – 384kHz (16/24/32Bit)
DSD: DSD64(1 Bit 2.8MHz) , DSD128(1 Bit 5.6MHz), DSD256(1 Bit 11.2MHz)

When playing audio, the data status indicator will illuminate one of the following colors:

Green: indicates the audio sample rate is 48kHz or less.
Red: indicates hi-res lossless playback.(Hi-res lossless refers to PCM 88.2kHz~384 kHz, or DSD64~DSD256.)
Magenta: indicates the M15 is performing the final unfold of an MQA Core stream.

OUTPUT INTERFACE
3.5mm standard headphone jack x1
4.4mm balanced headphone jack x1

OUTPUT POWER
3.5mm:RL=300Ω,Po=11.97mW, Vout(Max)=1.895Vrms,THD+N=0.00045%
4.4mm:RL=300Ω,Po=22.60mW, Vout(Max)=2.624Vrms,THD+N=0.00057%

FREQUENCY RESPONSE &THD
Frequency Response: ±0.1dB(20Hz-20kHz)
THD + N:0.0003%
DAC:ESS flagship USB DAC chip ES9281AC

Features:
DAC Capability
Low power consumption, no overheating
Long battery life, longer playback
Unparalleled ease of use
Plug-and-play, no drivers needed
Your HiFi, anytime, anywhere
Metal housing, transparent cover
Minimalist on the outside, stunning on the inside

The M15 contains two of Questyle’s patented CMA (Current Mode Amplification) SiP modules, for a total of four CMA amp engines. This quadruple drive amplification circuitry gives an outstandingly strong output that can drive almost any headphone. Questyle’s Current Mode Amplifiers are characterized by their small footprint, low voltage operation, and minimal power consumption. Current Mode amplification has a naturally low impedance, affording the M15 a bandwidth up to 1MHz, distortion as low as 0.0003%, and the ability to reproduce every detail hidden deep within any track.

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Unboxing:
Unboxing Experience was quite interesting for me. Come in a premium small black box . It was wise of questyle to use a small and light weighted box because in my country tax is sometimes implemented on the size of the box.
I got an extra type C to Ios cable & Black Leather Case (worth of 25$). But the original package does not have the ios cable. Apple product users need
to buy that cable separately at 20$
Usually the following items comes in the box

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1 x Questyle M15 Ultra Portable USB DAC/Amplifier
1 x USB Type-C to USB Type-C Low Profile Cable
1 x USB Type-A to USB Type-C Low Profile Cable
1 x Print Material (Instruction Manual & Guarantee Card)

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Appearance:
Small , handy , Compact size . Very light weighted. One of the side of M15 was covered with a glass faceplate which tends to see the inside beautiful structure of the M15
It also represents the transparency of the questyle that truely used inside the dongle. There are 2 ports on the dongle.
One is 3.5mm Single Ended (with CTIA support for headphones featuring phone calls) and the other one is 4.4mm balanced TRRS port. One the corner of the m15 there is a button to adjust the gain with high and low.
I was disappointed that there is no volume rocker button. I mean it is not mandatory but it helps sometimes. One the bottom of the m15 there is type c port to bypass the sound


Sound Impressions:
I have Actually used the high gain mode all the time when using the m15 with iems.its seems High gain always gave better output with great resolution to me. When using in high gain mode I have to set the volume to 50% . Its could be easily understand that the output has great amping capacity as well

The device I used was Samsung galaxy note 8 and my laptop. As mentioned on the specification I do not need any driver to install to use M15
The provided type c cable was good but I tried other type c cables as well. Those work perfectly without any issue. I liked the dd hifi tc05 instead of the stock cable. But I must say the build quality and material of the ios cable (Which needs to buy separately at 20$) was much better than the stock type c cable
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When i first plugged the m15 in my mobile and played a song from spotify I was feeling what is this, is that the small chilli with extreme hot. The details , the energy , the transparency , the separation (although provided by the IEM,but I got better using the m15 that couldn't be found with others dongles) was too much good
I am an iem guy so all of my testing unit was iem.

Questyle m15 is a kind of neutral sounding dongle, Sound is natural and crystal clear, Good clarity.
It was providing a non-colorized sound. very detailed and wide
While using it with IEMs in my room i didn't get any background noise with 50% Sound. It was like I was sitting in a quiet place.
It has really surprised me because I have never found my iems can detach me from the sound of the world. M15 got me recognized to my iems with their new identities.Because usually i didn't get this kind of good result
My Iems were Little dot cu red, Rose technics QT9 M2ks/QT 7 pro 2 , Tralucent 1+X plus 10th year Edition, tri audio meteor, Kinera skuld, Anew x1, Shanling
m15 was also providing me a holographic realization while listening to music and giving me synchronous rhythm.
There was not any hissing or noise while using it.

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The way it was delivering sound from low to high without any compression was really superb
Bass was good as well.Punchy, Not boomy.Sound does not fatigue. For me, excess bass could cause a headache. so bass was in good amount from the m15
I have tried to play some only vocal songs to better understand the vocal.Both male and female were great on the m15. The residue voices while finishing a line and about to start the next line was easily audible.
For songs with music the Voices were forwarded then the other instruments and I could easily separate where the instruments were playing.There were remarkable spaces between the instruments with good texture.
The way m15 upscale the whole music to upper grade without any issue was not only good but excellent. Airy vibes were present there as well
But sometimes I was facing some issues with treble. It was providing high pitch on some songs which really hurt my ear.
The soundage reproduction was accurate and had good depth.

I have sometimes used the m15 for about 3/4 hour at a stretch. The battery drain of my Samsung galaxy note 8 was minimal. The heat generated on m15 was very much low. I have used the leather cover with it. But i have checked the dongle temperature by removing the cover also. Does not produce any excess heat
It got heated slightly

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Conclusion:
I would like to rate it 5/5 after examining it for a long period of time.As I keep news about the local audio market in my country I get to learn that people are going crazy behind it. This has become their first choice if the budget is not a problem to them.
Spending 250$ for it is worthy but i would like to get a better type c to type c cable at this price point. Also Iphone users have to pay an extra amount of money for the ios cable. That could be provided free like some other brands.
I am hoping that the M15 will be my daily driver from now on . Because the output it is providing according to size is really praiseable.
For many people it was a problem for them not having a volume rocker button but i didn't miss the volume button that much. Yes it was needed for me to increase the sound sometimes but i could increase from the phone

Highly Recommended. The Questyle M15 can be bought directly from Questyle, Hifigo or from local dealers. Questyle has many dealers around the world.
wiesolos
wiesolos
I don't think that driving power of this dongle is huge by the given specs.
Questyle
Questyle

RemedyMusic

100+ Head-Fier
Questyle M15 - the "Revealer"
Pros: reference -grade sound quality
Excellent price-performance ratio
Appealing design and looks. The glass-way alone is a killer look.
Bread and butter features
Ground-breaking tech namely the CMA SiP modules that they have in their full-pledged amps
Neutral sound signature with good dynamics and not sounding too clinical
Enough power to drive full-pledge headphones as other reviewers claimed
3.5mm and 4.4mm outputs compare to M12 which has only 3.5mm
Super low floor noise even on highly sensitive gears
Direct compatibility for IOS devices which not all dongles possess (optional type-c to lighting cable can be purchased from Questyle)
Physical gain switch (low and high gain)
Superb performance in terms of technicalities (more of this later on)
Cons: Quite large in size for on-the-go setup
No physical volume adjustment (subjective)
The price can be steep for starting audiophiles. But hey, nobody said this hobby is cheap. The price is exactly $249.
Sound stage could have been wider (nitpicking)
Poor shielding causes interference aka EMI noise emitted from cellular data
Introduction:
Hello and mabuhay from the Philippines! Here we are for another audio gear review! And this time, a new kind of gear. A dongle! This will be my first attempt to review a dongle. If you have been around the audio community, you must have heard of AndyEF who initiated the Dongle madness. And what I have here is a top-tier dongle and I am quite blessed to have this as my first dongle. I am not as well-versed as Andy but I will try my very best to share my unbias and honest impressions here.
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Questyle is a company based in Shenzhen, China that specializes in quality amps. One of their product that is critically claimed by audiophiles is the CMA fifteen. This is my first encounter with them and I have not yet dived into their products. But by the looks of it, the company is low-key but makes exquisite and reference-grade releases. They don’t have a vast line-up but I think making it count is what matters to this company. Below is their website in English and feel free to roam around to know more about them.

https://www.questyle.com/language/en/home/

Special mention: I would like to express my deepest gratitude to Zach from Questyle for entertaining my queries and being nice and generous to me. He is the Product Experience Manager over there. You da man Zach!

With the M15, I would like to quote the concept of Questyle.

“In this complex world, we pursue simplicity.
The era of 5G has brought music streaming from smart devices fully into the mainstream. As more and more music platforms launch lossless audio streaming services, mobile hi-res audio has changed from a neat gimmick into a real and growingly popular way to enjoy high-fidelity music. However, it’s often impractical to use traditional HiFi audio equipment with your smartphone on-the-go, due to size and power consumption. To solve this problem, the M15 was born: it distills all of Questyle’s expertise and technologies into an amazingly powerful yet compact mobile DAC & amp.
Don’t be fooled by its small size. The M15 offers uncompromising performance and best-in class fidelity, giving you the ultimate portable audio experience.
Welcome to the world of truly mobile HiFi.”

DISCLAIMER:​

My opinions here are entirely my own. Any form of incentive does NOT in any way influence me. This is purely my honest, subjective impressions and experience with the gear on hand. I cannot stress more that you should take this with a grain of salt for we have different perceptions to sound and what we hear. I always try my best to stick with the stock accessories that come with the gear by default. You are free to try other methods such as tip rolling or cable rolling. Below are worth noting before concluding on what I say here:

  1. DAP (digital audio player, be it phone, laptop, mobile, or stationary setup)
  2. DAC or dongle or any external amp
  3. Ear Tips
  4. Cables
  5. Source of audio file be it offline FLACS or streaming services like Deezer, Apple music, Tidal, Qobuz, Spotify and the likes..
  6. Your playlist. It matters and is worth considering when reading from a reviewer's perspective. It is apparent that you get to know your favorite reviewer and what they are listening to leisurely and critically.

My reviews are more on how music sounds in my ears. I leave the technical stuff like frequency graphs and the physics behind the tech and drivers used to other reviewers.

Specifications:​


  1. DAC capability:
  • PCM: 32khz - 384khz (16/24/32bit)
  • DSD64 (1 bit 2.8mhz), DSD128 (1 bit 5.6mhz), DSD256 (1 bit 11.2mhz), MQA full decode
  1. Output power:
  • 3.5mm: RL=300ohms, Po=11.97mW, Volt (max) = 1.895 Vrms
  • 4.4mm: RL=300ohms, Po=22.60mW, Volt (max) = 2.624 Vrms
  1. Frequency response and THD:
  • FR: +0.1db (20hz-20khz)
  • THD + N: 0.0003%
  1. DAC: ESS flagship USB DAC chip ES9281AC

Packaging:​

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The outer box gives a premium feel to it with a very minimal design yet elegant. The box has good corners. The inner box slides to the right and you are greeted by documentation with Questyle’s concept on the product (mentioned above) and product usage. Then a warranty card underneath. After that, the M15 itself was placed in the middle. Another layer is underneath where the 2 cables are. 1 x USB A to type C. 1 x type C to type C. Questyle took the liberty of being extra generous and sent me 1 x Lightning to type C cable making it possible to enjoy this on IOS devices. You can purchase this for an additional price as it is an optional inclusion. And another bonus from Questyle, they’ve included the leather protective case that they gave for free on promo in the month of May if I’m not mistaken. A red colorway was given to me.
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Physical attributes:​

The M15 is a unique-looking dongle. Oozing with elegance and sophistication. The look-thru glass gives it away. It is the only dongle I know of, that has this design. Let me show you all its physical attributes with photos. A photo is worth a thousand words.
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Special note: The size of the M15 is quite large for a dongle and to be honest, it is not for an on-the-go setup. I can’t put it in my pocket along with my phone and it would be quite risky to let it hang with my phone, on commutes like the subway as the M15 has a decent weight to it. I’m the guy who moves around the house quite frequently and a lot of times I love doing my chores while listening to music. It is a struggle to move around with the M15 and I have to incorporate a belt bag to cater the M15 with my phone while doing my household chores like washing the dishes. Therefore, while the M15 still falls in the portable DAC category, I conclude it is still a semi-stationary setup with your phone.
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Features:​

The M15 has bread and butter features. It is not as fancy as other dongles with a screen where you can see the details of your track playing. But all the features that you need are here.

One thing missing here that I personally prefer is a physical volume adjuster. This is a minor caveat for me, but I understand other individuals who strongly prefer having this. Connected with my LG V30 phone, I don't mind it that much because I still adjust the volume level with the physical buttons of my phone. But if it were to be adjusted via a slider on the screen, it would have been a bit of a hassle.

A gain switch is present here. A very convenient feature. With my gears below 32 ohms, I use low gain, and for anything above 32 ohms, I use high gain. M15’s predecessor the M12 doesn’t have this feature.
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Available outputs are a single-ended 3.5mm, and a balanced 4.4mm. Another feature the M12 doesn’t have. If you have been an audiophile for quite some time, we all know balance output exhibits more out of your transducers and this will come in handy with your gears that offer balanced termination.

Next are the light indications. There are two lights here. One indicates if you are on low or high gain. Green means low gain, and red means high gain. As for the other set of light, it indicates the quality or codec of the music you are feeding it. Green for anything below 48khz, red for anything hi-res, and magenta for full MQA encoding.

And that’s it! Pretty basic right? But it’s all you need to enjoy your music with this dongle. No fancy screen here with sick transitions whatsoever. It emits a sense of being analog if you ask me. Which I am a fan of. Techs of the past and how they presented back in the days, appeal to me. And actually, it is easier to comprehend. Just look at the lights and you instantly know the quality of the file you are playing.

Now moving on to how M15 performed on sound…

Sound impressions:​

Special Note: I’m a firm believer that source matters. A dongle enhances our listening experience because it is not integrated with the phone or laptop we are using as our source. It has an impact on the sound we hear but it is not the primary factor that alters what we hear. As an example, if you have a transducer with a slow driver performance, a dongle will not make the speed of that driver perform faster. Maybe it would be enhanced but in a very subtle way. The primary sound presentation still depends on the performance of the transducer.

IEMs used for the entirety of this review are the Seeaudio Bravery Red limited edition, Kinera Idun Golden 2.0, Bqeyz Topaz, and Autumn. More on pairings later on.
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I will have a different format here addressing my sound impressions with M15. I will not dissect each frequency but rather lay them down as a whole along with the technicalities. Just purely expressing what I hear and the changes I hear compare to my other setups.
______________________________________________________________________________________
Ok straight to the point. The M15 is a “revealer”. Period. It reveals a gear, in my case mostly IEMs, strengths, and weaknesses. It has a neutral sound signature to my ears and with stupendous resolving capability. Not limited to gears, M15 reveals properly and poorly mixed tracks. I can’t say if this is a blessing or a curse, but there are tracks that I enjoyed before, that I don’t enjoy that much now, all because M15 showed me that it is indeed a poorly mixed track. Though not the most powerful dongle in town, it can handle most IEMs and some M15 owners have claimed that it can drive some headphones. Well decently at least. I still have to venture into headphones territory to back this up, but I do have one. A Samson SR850 32 ohms, and I’m listening to it as we speak, and I’m around 70% level giving me a good listening level.

The overall sound reproduction is crisp, transparent, and with brilliant transient speed. Neutral sources tend to be sterile and dry but M15 doesn’t present its sound this way. It remains organic, enjoyable, and with a wide dynamic range.

Mids and vocals made the most distinguished mark on me. Lush, rich, and rendered with good emotion. I’m a passionate musician, and I like my music moving me to places when I listen to them. M15 never had shortcomings in this department. Instruments sounded the way they should be and never felt artificial nor unnatural.

The lows are presented truthfully without any colorization with a snappy, and quick reproduction. I listen to a lot of jazz tracks, as I tend to look at how natural a gear can execute instruments in this genre and the lows are pinpoint. What you give the M15, it faithfully reproduces as natural and pure as it can.

The trebles have a slight elevation as I critically listen. Some of my gears appear to have added shimmer and sparkle on top but not at the expense of being sibilant.

The sound stage is above average. If I have to nitpick, it could use some extra expansion but negligible. I find my LG V30 via Hiby music app a bit ahead in terms of the sound stage but we’re talking minuscule difference here.

Separation is spectacular and I can conclude that elements portrayed by M15 seems to be laid down with good spaces in between them. Hence making it very entertaining to listen to. I find joy in deciphering what each instrument is contributing to the whole piece when listening to my favorite jazz tracks and M15 delivered effortlessly.

Imaging is brilliantly done as it places elements with accuracy. I can easily follow instruments let alone micro and macro details with good depth, width, and height as was intended by the engineers and producers.

Resolution and detail retrieval is the pinnacle attribute of M15 as I clearly hear small details and texture of instruments. Guitars portray their string vibrations, pedal presses from piano players are brought to light, and vocal strains of singers can be heard, strikes of drum sticks and hand slaps of a percussion player are just a few to mention. There are many details here so be prepared to hear new elements from tracks you know too well.

Performance:​

First off let’s start with the battery consumption of M15 with my phone. It is very energy efficient and doesn’t drain the hell out of my mobile phone. I mainly use the LG V30 for my offline flacs. I can enjoy a good 4 hours of playback and maybe even more if I’m not multitasking. This might be not enough for some but in my case, it is doable. If you prefer longer hours of playback, then a DAP will be more suitable for your needs. Or maybe a separate mobile phone solely for music playback will do.
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LG V30 quad dac x Hiby player music app​

The performance of the M15 is very smooth here. The floor noise is clean as black. Integration with the app is flawless. The Hiby app easily recognizes the M15. I run with exclusive mode on. No popping sound whatsoever when changing tracks. This is my main setup for mobility and portability.

Via UAPP:​

Smoothly integrated as the Hiby music app. With UAPP I find the sound a bit brighter. User interface responsiveness is also slower than the Hiby music app. Well, we are not here to discuss and compare the two mentioned music player apps. Let’s just say I personally prefer the Hiby music app. Nonetheless, the performance of the M15 is the same with the said apps.

Via Tidal on Android mobile phone:​

Still flawless and the app works with the M15 smoothly. Tidal Masters is indeed legit as the M15 emits a magenta led light when unfolding MQA. The Tidal app also offers an exclusive mode. Very handy. The app works with the M15 without any issues or hiccups.

Via Apple Music on mobile phone:​

Here I encountered some issues. In particular with running on an Android phone. I can hear some popping sounds in the background. Very unnoticeable in playback, but you will notice it when you are not playing anything. And by a big margin, the output is much softer. A more enjoyable experience with this app is on an IOS device. With my iPhone 7 plus, the output is much more accurate and louder. I did not use an OTG for this connection as the lightning to type c USB cable was provided. This comes as an optional accessory if you were to purchase the M15. If you stream mainly with Apple music, do it on an IOS device. Strongly suggested.

Via Macbook pro x Tidal:​

This is my go-to stationary setup. Exclusive mode is also available as with the mobile version. When I’m in the mood to explore and discover new tracks, this is my favorite. If you are not a believer of MQA, there is also a bypass option to do that. One caveat is when I’m seeking (forward or backward) an evident popping sound is produced. Not a deal breaker, but I often seek within my tracks especially if I’m critically listening to some parts of a song. Integration of the app here on a Macbook pro with the M15 is also smooth and with almost no issues.

Via Macbook pro x Foobar:​

This is my setup to access my offline flacs on a stationary setup. UI of Foobar is very basic and navigation is quite a pain. I like keyboard shortcuts but with Foobar on a Mac, is very primitive. The trackpad or mouse will be your best friend as everything will be done with it. Playback and true encoding of your Hires files are legit. Volume control is handled by the Mac OS. The volume up and down is very convenient so no dragging of the volume slider here, which I personally hate and is cumbersome for me. Performance and integration are legit with this app. UI just needs to be updated. I am eyeing the Roon but I need to research more on this.

3.5mm versus 4.4mm:​

The performance of both outputs is actually decent and commendable. Both possess excellent outputs and there is no reason to discriminate the 3.5mm over the 4.4mm. Balanced output is balanced and better in terms of dynamics, loudness, technicalities, driving power, and overall sound presentation. If you have the means to plug into the 4.4mm, please do. Nonetheless, 3.5mm is still very capable and not to be looked down upon.

Comparisons:​

I will mainly compare the M15 with my second source, the Hidizs ap80pro. This comparison is done with Kinera Idun Golden with the same song, approximately the same listening level, and on high gain mode since the Idun loves power. AP80pro running standalone, and the M15 is paired with an LG V30 android phone via the Hiby music app. Conducted both in 3.5mm single-ended output.

Track: Fool Truth by UDD, a local artist from the Philippines, mix and mastered abroad. I know this track too well, so I picked it for this comparison.

  • The floor noise on the M15 is much lower than on the ap80pro.
  • The ap80pro had more width, and the M15 had more height.
  • Listening level concerning driving power. M15: 8/32 (25%) ap80pro: 43/100 (43%)
  • The bass guitar in the intro is more textured and forward with the M15.
  • Vocals are more forward with the M15, with more details like the singer's pronunciation.
  • Both exhibit neutral sound presentations.
  • Drum kicks are punchier with the M15.
  • Vocal and instrument separation is better on the M15.

Conclusively, the M15 performs better on technicalities compared to ap80pro. The sound signature is almost the same on both gears. The M15 has a more pronounced mid-bass. The M15 outperforms the ap80pro by a noticeable margin. Still, both gears are very capable and exceptional for reviewing gears. Almost to no colorization and alteration on sound.
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Pairings:​

With Kinera Idun Golden​

Idun being a neutral set surprisingly paired well with the M15. I anticipated that this pairing will be too clinical or boring but that is not the case. The M15 brought the best out of the Idun, especially on technicalities. Not to mention the big improvement once used with the 4.4mm balanced output. This pairing is not void of being enjoyed particularly leaning towards the Hi-fidelity approach. Visit my full review of the Idun here: https://remedymusicaudiogears.blogspot.com/2022/07/kinera-idun-golden-20-my-sweet-prelude.html

With SeeAudio Bravery Red limited edition​

The Bravery is a more engaging pair with the M15 than Idun. A more colorful sound signature but maturely tuned. With exceptional imaging and instrument placement, the M15 brought it to another level. A perfectly balanced pair that is hard to ignore and neglect. The Bravery opens up significantly with balanced output. If you have a 4.4mm termination, put it to good use right now. The Bravery is very easy to drive with an 18 ohms of impedance. You might want to switch to low gain mode to avoid distortions.

Full review of the Bravery Red limited edition: https://remedymusicaudiogears.blogspot.com/2022/07/seeaudio-bravery-anniversary-limited.html

With Bqeyz Topaz​

If you want to go warm, relaxed, and yet technically capable set, the Topaz is one of my favorite pairings. I was once on vacation, and I brought the Topaz with me forcing me to listen to it for a couple of days since I have no other IEMs with me, and this is the most organic and musical pairing in my collection. The neutrality and clinical nature of the M15 compliment the warm and lush sound of the Topaz. When I’m in the mood for just relaxed listening, this is my go-to pairing.

Full written review of the Bqeyz Topaz: https://remedymusicaudiogears.blogspot.com/2022/07/bqeyz-topaz-soft-and-tender-hum.html

With Bqeyz Autumn on neutral filters​

If I’m in the mood for that extra sound stage, I go for the Autumn. The wide stage of Autumn compliments the somewhat intimate stage presentation of the M15. As per the sound, the Autumn sits nicely in the middle of the three IEMs above. The most balanced pairing of all. The Autumn boasts its earbud-like sound stage. And I just can’t get enough of it with this pairing.

Full and written review of Bqeyz Autumn: https://remedymusicaudiogears.blogspot.com/2022/08/bqeyz-autumn-game-changer.html

I have other IEMs in my collection, but these 4 will do as they are my most loved and “cannot live without” sets. All aspects above are very subjective. Please take it lightly with a grain of salt. Your mileage will most likely vary.

Minor Issues:​

As it breaks my heart to address some issues on an impressive gear, I still decided to include the following in this review. It has been a topic among us owners of the M15 at a thread at head-fi. It is regarding interference or what they call EMI noise. To be honest, I didn’t notice this until just recently. And yes the M15 emits a noise that is caused by cellular data from our phones. There are 2 ways to eliminate this.

  1. If your phone is connected to Wifi, you’re good. No interference.
  2. Turn on airplane mode.

The downside here is if you stream your music a lot, using cellular data, then you’re in trouble. Some owners are concluding that the M15 has poor shielding on interference from outside. Now even if I’m playing my offline flacs, but my cellular data is on, and not connected to a working Wifi, yes I have the interference. I have an attitude of being a purist when it comes to my music, and I’m really downhearted to experience this.

Personally, I mainly stream my music with Tidal on my laptop, and with this setup, fortunately, no EMI noise is audible. So for those who stream their music on the go, you might want to consider it first before pulling the trigger on the M15. But as I concluded in this review, the M15 is awkward to use on the go. So most likely, you will use the M15, on Wifi, streaming. You are safe if this is the case. Do be aware that the EMI noise is very minimal. It easily drowns out when you are playing your music. It’s just I’m a purist somehow, that knowing something is in the background, bothers me.

I would like Questyle to notice this issue, so they will consider it with their future releases, and potential successor of the M15. Questyle, please take this into consideration strongly.

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Verdict:​

The invasion of the dongles was mind-blowing in the audio community. I would like to commend AndyEF aka OspreyAndy for his #donglemadness for pointing me in the right direction. He saved me the trouble of going all through the almost hundred releases of dongles out there.

What caught my interest in the M15, to be honest, is its looks and design. Let us admit it, if it looks good, we hope it sounds good too. Apart from looking sleek, the M15 is my best experience in terms of source. My best one yet. I’m a technical-oriented listener, for the main reason that my main profession is being a pro-gigging musician. I always have a sweet spot for critical listening and I really have a high benchmark even if the sound is towards clinical presentation. But the M15 is not at all like that. It has rich dynamics, soul, and emotion portrayed character. It is just a very neutral and transparent sound presentation.

Driving power is very decent although not the most powerful dongle in town. It is surely an upgrade from my Hidizs ap80pro. M15 at 25% listening level while the ap80pro at 43% listening level. Driving full-sized cans I still have to explore. I have an Audeze headphone on the way, maybe 2 weeks from now, and I will update this review once I pair the two.

As for portability, I have some caveats on this. My listening setup with the M15 is somewhat a semi-stationary one. It is too large and heavy to be left hanging with my phone on commutes and is awkward to move with it while I’m moving around the house doing my daily routine and chores. It is not a true on-the-go setup in my case.

Anyways I don’t want to repeat what I said in this review so I would advocate the M15 to those:

  • Who prefers a neutral source
  • Who has a priority on technical aspects
  • Who loves critical listening
  • To reviewers who need to accurately judge gears
  • To those who want to be rest assured that what they are hearing has no color added
  • To those who want a resolving source

And that concludes my review of the M15! Again this is my best source yet! And as for reviewers who have more expensive source gears, they say that this punches way up to the caliber of 500$ price range sources. And you can enjoy that kind of quality for half the price! The M15 retails at 250$. I hope you enjoyed reading my impressions and a video version of this will be out soon.

Special mention to Eric Lab for putting a good word for me with Questyle giving way to getting my hands on the M15.

As always, love the music more than the gears! And your mileage may and most likely vary. Cheers, and catch you on the next one!

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BonGoBiLai
BonGoBiLai
Great review. I rarely use cellular data therefore never noticed EMI issue. Mildly disappointing given its the best dongle being sold right now, toppling even mid fi desktop setups
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ByrnesK
Great review.

This is a fantastic device that can in some cases blow past mid range home setups and at such a small compact size that is a real feat of engineering, I appreciate you bringing up the EMI noise issue while a lot of reviewers would skip over the issue or did not test for it, at the end of the day this is marketed as a portable solution and a lot of people would be streaming music on the go via mobile data and not have offline libraries that clog up memory on your phone.

For an offline library I personally would prefer a DAP for on the go rather than using a dongle, a dongle imo is meant for on the go streaming music so you don't have to bring another physical device or your entire offline library with you. It is supposed to be easy, effortless, plug and play option that takes up little space whether thats physically or in terms of memory space on your phone.

P.s. this is how I feel on the matter and may not be what the majority of people are thinking.

Sunstealer

500+ Head-Fier
Questyle M15 USB DAC/Amplifier: Arisen my senses!
Pros: Design - that glass top is a striking choice
Power
Balanced sound
3.5mm and & 4.4mm outputs
Cons: No physical volume buttons
Glass top makes me worried about transporting it outside of a good hard case
The M15 was sent to me by Questyle after I reached out about another product. Many thanks to @Questyle for facilitating this. I am not expected to return the product and this will not influence my opinion of it or Questyle in any way.

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It’s in Our Hands:
OnePlus 6 & Neutron Player
ER2XR, 4.4mm balanced stock cable, Westone foam tips
TRI I3, 4.4mm balanced silver cable, foam tips
Playlist made up of MP3, FLAC and DSD256 tracks.

Unravel:
The M15 arrived in a black matchbox-style cardboard box, USB C cable, USB A-C cable and a brief diagrammatic manual. A green leather case was included and fits very snugly. So well that I cannot remove the M15 at all! I’m sure it would come out if required but would take a bit of gentle persuasion. The glass top shows off the circuitry and 2 status LEDs for sample rate and gain. There is a hardware gain switch on the side.

Playlist:
I listened to the whole of each track but specifically for the timed parts mentioned. I used the balanced output in low gain.
  • Happy Cycling | Boards of Canada - from 5:06, percussion and bass synth
  • Waters Deep | Bent - from 4:45 bass line, female vocals and higher register synth
  • Man (Live at the NEC) | Level 42 - from 2:20, Allan Holdsworth guitar solo
  • Play Me (Live at Reading 2001) | Level 42 from 3:57, bass guitar solo, electronic bass
  • Two Solitudes (album version | Level 42 - from 2:42, acoustic guitar solo
  • Peace Bird | Genius of Time - from 2:38 grinding sub-bass refrain then 4:40 sub-bass line, percussion
  • On a Clear Day | The Peddlers - from 1:00 strings and harp
Desired Constellation:
ER2XR:
There is an extended sub bass (not something the ER2XR is particularly known for) with a surprising but very welcome touch of viscerality. Percussion is clean, not splashy or sibilant which can be an issue if the source or recording is neutral or bright. Male and females voices are natural, if a little thin. Similarly, guitars and keyboards are tonally correct but lacking slightly in body. I did not feel that there was a particular emphasis in any register and the M15 was showing me what the ER2XR could do. With silicone tips I noticed a cleaner sound with less bass warmth.

TRI I3: This has a mild U-shape FR and the M15 allowed it to shine. The soundstage is wide (a valuable property of the I3) with clarity, focus and separation. Again, the sound was clean and slightly warm, with visceral sub bass, smooth vocals and extended treble. In essence, exactly what the TRI I3 should sound like.

Mutual Core:
I hope that you get a sense of where I’m pitching the M15 in terms of sound. I feel it is balanced, detailed and natural. The music I listen to sounds faithful, uncoloured and tonally correct. The transducers I used gave an accurate account of themselves with nothing added to or subtracted by the M15.

Holographic Entrypoint:
For comparison, I fired up my Cayin RU6, a completely different beastie. Balanced output, low gain, non oversampling mode. The hardware volume buttons are a very welcome feature. The RU6 soundstage is far wider than the M15 with a warmer, darker tilt to the sound. That isn’t to say that it isn’t detailed, just differently so. Notes are fuller, sweeter and just…beautiful to listen to. The analogue bass of the BoC track is a great example. I notice smoother transients with some loss of attack and bite to guitars and synths. Vocals are smooth and warm as you might expect. The registers just have…a density and weight that is difficult to describe but so joyous to experience. The RU6 is equally superb but in a totally different way. I use it at my desk and took it to Canjam as a cross-reference. This is like a full-bodied stovetop coffee from Brazil.

Generous Palmstroke:
The M15 is a fresh, clean and natural sounding device that shows you the best of your earphones. I used it on my desk and took it to the London Canjam as a representative source. I liken it to a fruity V60 pour-over coffee from Ethiopia.
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asifur

100+ Head-Fier
Questyle M15 : Best Performing Dongle... Redefining dongle performance!
Pros: + Small & Pocketable
+ Transparent design and posh looks
+ 4.4mm balanced connector support
+ Separate Low & High gain modes
+ SIP & CMA resulting in significantly cleaner & transparent output
+ Class AB amplification which is rarely found in a dongle
+ Can easily power IEMs and a lot of headphones
+ Excellent Staging & Imaging
+ Superb Separation
Cons: Literally nothing I could find!
Questyle M15 : Best Performing Dongle... Redefining dongle performance!

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Summary & Objective:

The @Questyle M15 is the second dongle release by Questyle in 2022, with balanced 4.4mm support and comes with some great features such as SIP and Current Mode Amplification which are generally found in portable players. It promises excellent performance and delivers exactly as promised and more.

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Introduction:

The @Questyle M15 comes with excellent build quality and superb sound performance - not mentioning any price brackets here as soon you will find that it's performance goes way beyond it's price. It is the first ever dongle to feature SIP and Current Mode Amplification featuring Class AB grade amplification .
The Questyle M15 is priced at $249.

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Disclaimer:

This unit was sent by @Questyle for the purpose of an honest review.
Everything mentioned in this review are purely my own based on my experiences with the Dongle DAC/AMP.

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Design, Build & Features:

I wouldn't want to make this a very long review by describing each feature but for people who want to know, here are some extracts from the Questyle website.
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Specifications:

The Questyle M15 comes with $249 price tag and the specifications are as below:

https://questyleshop.com/products/m15

Questyle M15 uses all of Questyle’s expertise and technologies into an amazingly powerful compact mobile DAC & AMP.
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NOW LET'S TALK ABOUT THE SOUND....
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Items Used for this Review:

IEMs:

IEMs of different ranges:
below $300: Kinera IDUN GOLDEN, 7Hz Timeless, @MOONDROP CHU, TINHIFI P1MAX
$500-700: @CampfireAudio Holocene
$800 - 1500: @Sennheiser IE600, @DUNU-Topsound ZEN PRO, @CampfireAudio Dorado 2020, @Audeze Euclid
$1500 - 2500: @UniqueMelody MEST MKII, @Softears Turii Ti
$3000: @Vision Ears EXT

Well these are the ones I have with me presently... and have used for the review.


Source : iPad Pro, iPad Mini 6, iPhone 13 Pro max, Laptop
Streaming Source: QOBUZ

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Tracks Used:
The tracks I have used can be found from the below playlist that I have used and generally use for most reviews...


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QUESTYLE M15 Sound Impressions in Short:

Tonality:


Despite the ESS DAC based architecture, the M15 has a very neutral tonality while ensuring clear, crisp & transparent sound delivery.

The BASS:

The Bass sounds just Superb. Bass has details in the sub-bass region and is thick and creamy with enough muscle in the mid-bass to make the instrument attacks sound very natural and realistic. In tracks like : "Anna R. Chie (Remastered) - Konstantin Wecker" and "Dreams (2001 Remaster) – Fleetwood Mac" you can feel the the deep attack of the different instruments with just enough details. The thumps and slams are very enjoyable. The layering & separation is also superb and you can distinguish each instrument from the other one easily.

The MIDS:

The Midrange is excellent in terms of every single element. It is able to produce an good creamy smooth and textured midrange that is soothing to the ears while having enough details and layering in it. The vocals are natural and both male and female vocals come with good amount of details. Instruments sounded natural and can be identified easily from the other instruments owing to superb separation capabilities. In tracks like: "Anchor - Trace Bundy" and "Ruby Tuesday - Franco Battiato" while you will love the overall midrange specially transients of the guitars, violins etc... instruments and the vocals.

The TREBLE:

The Treble is very natural with enough extension & air as the track commands. It has enough details and despite being very natural it doesn't come with any harsh peaks in the treble region.

STAGING & RESOLUTION:

The staging and resolution is excellent and significantly better than any other dongle that I have come across so far. Resolution is also better than any other dongles and provides a very transparent representation while maintaining clarity and sense of direction. Tracks like: “ She Don't Know – Melody Gardot” or “Bohemian Rhapsody (live aid) – Queen” sound good & enjoyable. In this category this can rival many $500 - $800 DAPs easily.

Amplification:

This is clearly a competitive advantage for the M15 with the SIP and Current mode amplification, it is able to provide class AB or better quality amplification which is miles ahead of any other dongle in whatever price bracket.

Pairing:
The M15 makes an ideal pair with just about any IEM. It pairs well with each & every IEMs that I had tried from the various price ranges and various traits.
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Comparisons:
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Based on many people's request, I had been able to compare the M15 with 8 other dongles on which I had done some facebook posts in the head-fi group already.
Links to those posts are below:

https://www.facebook.com/groups/headfi.org/posts/10160114346144736/
https://www.facebook.com/groups/headfi.org/posts/10160143803149736/

I will not go through much details here and will basically be summarizing my impressions based on the different

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The Contenders:

The 8 dongle contenders against whom I have compared the M15 are below:
Below list is random and not based on any particular trait...

- @iFi audio Go Blu : $199
- @iFi audio Hipdac 2 : $189
- @iFi audio Go Bar : $329
- LUXURY & PRECISION W2-131 : $319
- Cayin RU6 : $249
- @Shanling M3X : $399
- XDUOO LINK 2 BAL : $149
- DDHIFI TC44C : $119

Here, as you can see the @Questyle M15 falls in between the price ranges above priced at $249 and is closest priced to the Cayin RU6.
The @iFi audio Go Bar and LUXURY & Precision W2-131 are higher priced, while others are priced lower. I have kept the Shanling M3X DAP also as that comes in similar price range and close to the iFi and L&P ranges at $399.

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I will not be ranking the above mentioned dongles here, rather I will be sharing comparative impressions with the M15 here.

COMPARATIVE IMPRESSIONS:

Below $200 Range:
The following dongles fall into this range: DDHIFI TC44C, XDUOO Link2 BAL, iFi Go Blu, iFi Hipdac 2. None of these dongles are as resolving or can provide as clear and transparent presentation as the M15. In terms of Staging, Imaging & Separation the M15 is significantly ahead.

$200 to $300: Only the Cayin RU6 and the M15 fall into this category. both are superb performers and I love them both, However, the M15 excels in terms of clarity and transparency and also in terms of staging and separation.

Above $300: The L&P W2-131, iFi Go Bar and the Shanling M3X fall into this category and are more expensive than the M15. While some of them might be more powerful in terms of specs than the M15, the quality of amplification in the M15 is significantly better than any of these and the difference is quite easily audible.
The level of clarity & transparency that the M15 brings onto the table is truly superior and also the level of saturation and sense of direction in the imaging department. This is not to say that the other dongles are not good... Just that the M15 is audibly better.

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Conclusion :

After comparing all those dongles above, if I have to pick one based on my preferences, I would pick the M15 in a heartbeat. It is significantly better than any dongle that I have come across till date and redefines the performance expected from a dongle..
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fotis1972
fotis1972
I have meze 99 classic with fiio x5 ii+ fiio e12, and I was thinking to upgrade. Thinking to go for a dap about 700 euro or a dongle (questyle m15) using with phone, what is better option, I listen pop disco rock hard rock heavy metal. With my fiio duo now have very punchy deep bass, which I want to keep it with my new purchase, but also want the most juice from my meze. Thanks for your review and your time
asifur
asifur
@fotis1972 Though I don't have the gears you mentioned, in my own experience - I had found M15 to pair well in most cases if not all.
T
theElk
@fotis1972 M15 would be the best bang for the if you have no iPhone. The current Limitation on iPhone lightning connectors will ruin the Experience if you need something around or over 400mA out of the Phone.

BonGoBiLai

100+ Head-Fier
The Little Dongle That Could
Pros: 1. Reference grade sound
2. Detail retrieval
3. Dynamics, Extreme precision
4. Excellent sibilance control
5. Extension
6. Brilliant heat and battery drain management
7. Manual gain switch
8. POWER
9. Punching far above its price point
Cons: 1. Soundstage is just adequate
2. No lightning adapter
3. Provided cables are very stiff
(The pros far outweigh the cons/nitpicks)
Dongles have suddenly skyrocketed in popularity after Apple decided to ditch the headphone jack in favor of airpods (which worked flawlessly as airpods generate unbelievably huge amounts of revenue and profit for Apple) and the whole smartphone industry followed suit. Initially there were only budget options; Cheap, decent but also rough around the edges and underpowered. But in recent months, we have observed a sudden boom in ‘premium quality’ dongles costing 150-400 USD that are somewhat blurring the line between ultra portability and mid fi desktop class sound.

That being said, Questyle M15 is probably the best all rounder in the premium dongle class right now. Questyle, although a bit obscure in the crowded Chi fi scene, has never made a product that isn’t great. Their first foray into the ultraportable dongle market was the underrated but amazing for the price M12, which I preferred to iFi Hip DAC even. M15 is the full fledged evolution from M12 to a far more capable, incredibly impressive little device.

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Disclaimer:

This unit was sent by Questyle to Sajid Amit, reviewer at Amplify Audiophile Show. I work with Amplify and what follows are thoughts and opinions that are solely mine.

Unboxing, build quality and ergonomics:

Unboxing experience is great. Comes in a simple and minimalistic black cardboard box. 2 short USB cables are included. One USB A to type C and another is type C to type C. Build quality is as expected from Questyle, Sublime. Extremely good finishing all around, fabulous weight distribution and skin feel. Both 4.4 mm and 3.5mm connectors feel solid and premium.

Aesthetically M15 is probably the most unique looking dongle out there right now. Internals are entirely visible through the acrylic window on one side. This gives the M15 a very nerdy, over the top yet refreshing look (internals are neat looking as well, adding a massive bump to the overall aesthetics).

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M15 is a bit bulky for a dongle but the weight distribution, like I’ve already mentioned, is excellent, therefore ergonomics was never an issue for me.

Important Features:

M12 was great but had a few feature flaws that have been addressed in M15. M12 had automatic gain meaning low sensitivity low impedance headphones and IEMs would trigger low gain when high gain is necessary. M15 has a manual gain switch that can be flipped anytime to make itself compatible with all the headphones and IEMs it can power. Another big addition is the 4.4mm balanced out which is incredibly powerful for a small form factor device (will discuss in detail later). M15 supports fancy codecs like MQA and DSD and it’s a proper MQA decoder, not a renderer. Therefore a good option for MQA believers.

M15 is also modular meaning you can use any compatible type C cable you like on a large variety of devices

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Specs:

  • DAC Capability:
    • PCM: 32kHz – 384kHz (16/24/32Bit)
    • DSD64 (1 Bit 2.8MHz), DSD128 (1 Bit 5.6MHz), DSD256 (1 Bit 11.2MHz) MQA Full decode
  • Output Power:
    • 3.5mm: RL = 300Ω, Po = 11.97mW, Volt (Max) = 1.895 Vrms, THD+N = 0.00045%
    • 4.4mm: RL = 300Ω, Po = 22.60mW, Volt (Max) = 2.624Vrms, THD+N = 0.00057%
  • Frequency Response and THD:
    • Frequency Response: ±0.1dB (20Hz-20kHz)
    • THD + N: 0.0003%
  • DAC: ESS flagship USB DAC chip ES9281AC
  • Output Interface -
    • 3.5mm standard headphone jack x1
    • 4.4mm balanced headphone jack x1
Sound:

M15 is the most reference sounding premium dongle right now period. The first thing I noticed immediately was the sheer transparency and details it was pushing. I couldn’t believe I was listening to a dongle and not a full fledged mid fi desktop device. What's most impressive is that this transparency and neutrality doesn’t come at the expense of musicality. Yes M15 is high res and highly analytical but the common denominations associated with these qualities like sterile and dry don’t apply here, at all.

Bass is one of the best I’ve heard in DAC Amp regardless of price and really brings out the best from what your headphones/ IEMs are capable of. There is no exaggeration, no bump in any bass frequencies. Just full bodied, snappy and accurate bass with brilliant extension. For example there are not many DAC amps especially under 1k that can do justice to Focal Utopia’s bass capability. But with M15, the full potential of Utopia’s extremely dynamic and fun bass reproduction is unleashed. I had similar results in bass performance with every other pairing I tried.

Midrange is lush and full bodied but there is no coloration. This is a very hard feat to pull off but M15 does this effortlessly. This results in an even performance between male and female vocals. Instrument timbres present in the midrange also sound as they should in real life, accurate and natural.

The brilliance of midrange and bass continues further in the treble region. If I have to describe the treble in 3 words, those would be extended, precise and controlled. There is no unnatural boost to any region to pump in artificial air, no digital sheen resulting in plasticky, glassy edges all over the music. Nailing the treble region is what's missing from most dongles from my observation. They are often treble boosted in order to generate a sense of detail and air, or too polite making everything dull and boring. M15 is probably the only dongle that blurs the line between precision and musicality in the treble region with resounding success

Technical performance:

M15 is a monster in this regard. Imaging is stupendously good and so are separation and layering. I can pick up every single instrument, every single layer in the vocals and bass but it's effortless and never becomes a chore. Dynamics and speed is easily among the best I’ve heard under 1000 USD regardless of form factor. My only gripe here is the soundstage which is adequate but not very large but it’s a miniscule issue in my book and not noticeable unless you frequently AB between different DAC amps that sound wider.

Driving power. Heat management and battery drain:

M15 is an anomaly if power and battery drain is considered. It can power almost anything except outliers like Susvara, HE6SE Abyss ETC. On high gain and balanced out, I can hardly turn up the volume beyond 30/40 on Arya Stealth and Edition XS. And by driving power I mean driving properly, not just driving loud. M15 adopts Questyle’s bespoke current mode amplification tech which uses CMA modules instead of traditional OP amps. Therefore, actual driving power is much higher than the specs suggest. I also like how M15 doesn’t gimp SE out in favor of BAL. Both are equally good and the only difference is in power and to some degree, separation (barely noticeable).

Heat management is exceptionally good. It doesn’t get hot/warm at all on low gain and heat management in high gain balanced out is still impressive. Gets slightly toasty and warm but never alarmingly hot like many super compact DAC amps and dongles tend to do.

Battery drain is minimal despite its exceptional driving ability. This is a highly overlooked advantage that premium dongles often fail to nail. Minimal drain means massive boost in practicality and battery life of the host device. M15 does a fantastic job in this regard

Synergy:

Being reference sounding means synergy will be good with almost all headphones and IEMs out there. The way M15 handles and mitigates sibilance and uneven peaks bolsters that even further. Almost all my headphones and IEMs that could be powered by it sounded great. It performed extremely well with both Arya SE and Edition XS and every single I've thrown at it including IER M9 and Legend Evo.

My friend and mentor Mr. @Sajid Amit even tried his Abyss AB1266 phi TC on it and white it didn't perform to its full potential, performance was still more than satisfactory


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Minor gripes:

1.
Glass window is cool and all but glass is glass and glass breaks. You need to be extra careful. My personal solution to prevent fingerprints and scratches was buying a random hydrogel protector for smartphones (dirt cheap), cut it to size (6 cm * 3.2cm) and applying it on the window. There is a pre installed screen protector already present though but being cautious always pays.

2. No physical volume adjustment. Not necessary in my book though. Controlling volume from smartphone is more ergonomic and you can always control volume via keyboard or mouse side buttons on pc

3. Provided cables are very stiff albeit robust. Softer materials would’ve been more ergonomic

4. Too perfect to nitpick any further lol

Conclusion:

M15 blurs the line between ultra portable and mid fi desktop performance. I'd even like to hyperbole a bit and say its a proper high end Hi fi device. A true champion and breakthrough in the ultra portable Dongle DAC amp scene. Kudos to Questyle for making something affordable (relative to their serious stuff) and retaining their magic even in small form factors.
BonGoBiLai
BonGoBiLai
Yes M15 will be a significant technical leap. I generally run my Sony IER M9 off it and man, It sounds massive off M15. Like a full fledged kilobuck over ear. Also extremely good performance with Hifiman Edition XS and HD 650
RemedyMusic
RemedyMusic
I really like the way you describe what you hear here. Thank you for the review. I hope mine gets send soon. 😁
BonGoBiLai
BonGoBiLai
Thank you for your kind words. Hoping you'll like it :gs1000smile:

ywheng89

100+ Head-Fier
Questyle M15 Long Term Review
Pros: Very dynamic sounding and engaging to listen to
Neutral and uncolored sound
Plenty of driving power
Not analytical nor sterile sounding despite sporting neutral signature
Cons: Does not bundle with Lightning's adapter (Nitpicking)
Questyle M15 Long Term Review

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Intro
Questyle is a brand I believe most audiophiles are aware of. They are famous for their CMA technology (Current Mode Amplification),you may read more about their CMA in this link if you are interested. Today we have M15 with two independent CMA SiP modules compared to M12 which is M15’s predecessor with only one SiP module. Today I will evaluate the performance of M15. Now,I may sound a little biassed and shilling this product,but trust me,once you have listened to it,it is very hard to put it away,of course,provided that the sound signature is your preference.


Specifications and Diagram (Grabbed from Questyle’s Website )
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DAC Capability -
PCM: 32kHz – 384kHz (16/24/32Bit)
DSD64(1Bit 2.8MHz) , DSD128(1Bit 5.6MHz), DSD256(1Bit
11.2MHz)

Output Power -
3.5mm:RL=300Ω,Po=11.97mW,
Vout(Max)=1.895Vrms,THD+N=0.00045%
4.4mm:RL=300Ω,Po=22.60mW, Vout(Max)=2.624Vrms,THD+N=0.00057%

Frequency Response and THD -
Frequency Response: ±0.1dB(20Hz-20kHz)
THD + N:0.0003%
DAC:ESS flagship USB DAC chip ES9281AC

Output Interface -
3.5mm standard headphone jack x1
4.4mm balanced headphone jack x1


Packaging/Build Quality
M15’s packaging is fairly minimalistic and elegant to me. No fancy layering and huge space wastage,it gets the job done and looks elegant and minimal. The package came with two USB cable,one type c to c,and another type c to type A. I received this unit during the promotion period hence it came with a leather protective case which I find it to be very good from protecting the unit from scratches.

In terms of build quality,the whole device feels very solid. Body’s panel is made out of metal and the front panel is a transparent cover which allows you to view the internals of the M15.Very nice looking piece of hardware in my opinion.

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IEMs used
  • Letshuoer S12 (Planar)
  • TinHIfi P1 Max (Planar)
  • FAudio Major (Single DD)
  • Moondrop Aria Snow (Single DD)
  • Rose Technics QT-9 MK2S

Source used
Foobar2k -> Questyle M15
Apple iPhone 12 Mini Apple Music -> Questyle M15
Foobar2k -> TRI TK2

General Features
M15 is equipped with a gain switch which is a very welcoming feature that allows us to manually control the gain considering M12 does not have a gain switch but an automated switching instead.

M15 has got a see-through front panel which reveals the circuitry of M15,i personally like the appearance a lot. There are two LEDs which indicate whether M15 is on Low/High gain,and another LED which shows the data rate. Refer to the diagram under specification for more information.

Testing the battery drain of M15 on my iPhone 12 Mini,gotta admit it drains quite a bit of juice from my device. Do take into consideration that the iPhone 12 Mini itself has a smaller capacity battery.

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Driving Power
Unfortunately,I do not own any headphones/IEMs that are hard to drive. Let’s just say it is able to drive anything that I own even on low gain mode. FAudio Major, TinHifi P1 Max,Letshuoer’s S12,

Sound
This is my first time testing out Questyle’s product.I have heard many great things about how good they sound across their product line. M15 is no exception either,to my ears,they are uncolored and fairly neutral sounding.Dynamic sounding but they are not sterile or analytical sounding.Very enjoyable and pairs well with most of the IEMs i have. Prior to writing this review, I have been using M15 extensively for at least 3 weeks on a day to day basis averaging 3-4 hours a day.

Bass
  • Clean,fast and tight bass,not muddy at all
  • Good texture/note weight and enough warmth for the bass texture
  • Sub-bass rendition on M15 is clean and not emphasised,it delivers the sub bass as it is. An example of slightly emphasised sub bass is on Xduoo’s Link2Bal,on the same IEM,it sounds different on both DAC/AMP in terms of the sub bass rendition
  • Very good impact and note weight
  • Bass doesn’t bleed into the mids and it is very capable in handling busy tracks like Slipknot’s Duality,not a tinge of muddyness spotted

Mids
  • The midrange reproduced by M15 is very lush and organic sounding to my ears,they are in no way cold sounding nor sterile,maybe titling to the warmer spectrum a little,at least to my ears
  • Both male and female vocals has got good textures to them
  • Instrument’s timbre such as piano sounds very natural to my ears
  • Upper mids are are not harsh and very pleasant to listen to

Treble
  • I find the treble on M15 to have good extension and non fatiguing to listen to
  • It has got plenty of details,both micro and macro but never at once it sounded too analytical to my ears,even when you crank up the volume,it remained very pleasant to listen to
  • Treble never sounded cold,instruments does not sound splashy at all
  • The air and sparkle region is also nicely reproduced

Soundstage and Imaging
  • M15 doesn’t reproduce an overly huge soundstage,instead i would say it is reproduced in a more accurate stage size,Xduoo’s Link2Bal for example,the soundstage reproduction certainly sounds bigger on Link2Bal compared to M15,but it does feel a little artificial and M15 does not made me feel that way
  • The soundstage reproduction has got good depth and height,but it doesn’t give you that kind of “out of head” feeling
  • Imaging is also very on point,instruments can be identified easily and layered properly

Comparison (TRI TK2)
  • Both M15 and TK2 sports DAC from ESS albeit different model
  • To my ears,I actually enjoy the M15 a lot more compared to TK2,TK2 to me sounded a little sterile and dry?
  • M15 is a lot more versatile when it comes to IEM pairing,it seems to synergize well with the IEMs that i have listed above,even some other IEMs like HZSound’s Waistdrum,TinHifi’s T1S,and even Final Audio A4000,WaistDrum and Final Audio A4000 on TK2 are not a good pair as TK2 kind of made both of them sound brighter than they already are
  • In terms of driving power,i believe both should perform on the similar level although i do not have any hard to drive gears nor any measurement tool to test it
  • In terms of soundstage, TK2 seems give a taller sense and slightly wider soundstage compared to M15
  • In terms of technicalities,they are more or less similar to my ears

Final thoughts
This is my encounter with Questyle’s product and now i’m hooked! It is very exciting to see such a product in a small form factor that’s capable of delivering reference class sound without breaking the bank considering the sonic performance that it brought along with it.

It’s safe to say,this will be my reference dongle dac/amp and I will be using it extensively for any IEM/headphone review moving forward.

Highly recommended piece of hardware and i will gladly give this a 5 star without any doubt!

*Questyle M15 was sent to me f.o.c for the purpose of this review, I thank Zach from Questyle for the opportunity. I am in no way compensated nor influenced to produce this review.

Questyle M15’s Product Page

https://www.questyle.com/language/en/m-15/

Get one here! (Non affiliated)
https://questyleshop.com/products/m15

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NymPHONOmaniac

Headphoneus Supremus
A more than capable dongle
Pros: -Clear and neutral sound with lively dynamic
-Excellent Pace, rythm and timing (PRaT) performance
-Great imaging with open spatiality
-realist timbre with good transparency
-weighty dynamic
-clean linear current amping
-gain switch
-more powerfull than the specs suggest (75mw@32ohm)
-doesn’t get hot or drown battery too fast
-best ES9281C DAC implementation i heard
-great balance between technical and musical audio decoding
-versatile pairing with high sensitivity and high impedance IEM
-unique geeky design for circuit board lover
Cons: -while powerfull, it will struggle to drive very low sensitivity IEM or Headphones
-micro-definition isn’t the cleanest nor the sharpest
-bass and treble seem just slightly tamed
-glass cover can be scratched and is worrysome for durability
-protective case make it hard to use gain switch
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TONALITY: 8.8/10
TECHNICALITY: 8.8/10
CONSTRUCTION: 8.2/10
AMPING POWER FOR THE SIZE: 8/10
SOUND VALUE: 8.5/10

QUESTYLE
is a chinese high end audio company specialize in amplifier, DAP and DAC-AMP. They have been around since 2015 and are known for their high end DAP like the well receive QP1R and QP2R, as well as for their deskop amplifier and lately for their portable DAC-AMP (dongle).

Another thing that Questyle is know for, it’s their patented Current mode amplification technology, which permit to achieve class A amplification quality in a more compact factor. All their products use this type of amping circuitry which is acclaim by audiophiles.


Today, I will review their latest portable DAC-AMP release, the M15. Priced 250$, this mid-tier dongle use a sabre ES9281AC DAC with four CMA (current mode amplificator), which promise highly dynamic sound rendering as well as top of the line audio performance.
Let see in this review if the price is right for such a small DAC-AMP.



CONSTRUCTION​

Unique you say?

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The M15 have a very original design that is sure to catch the eye and even make you suddenly curious about audio circuitry. Its made of metal body with the top all made of glass that permit to see the whole circuit board, including dac and amps chips.

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This design is wise too, since it have 2 light indicator on the board, one for data transmission and other for gain selection. Data indicator light color will change depending of codec rate, green for anything under 48khz, red for anything hi res between PCM 88.2kHz~384 kHz, or DSD64~DSD256 and magenta for MQA streaming. Gain light color will be green for low gain and red for high gain. This is very practical yet subtle in it’s presentation.

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Rest of body is made of metal with a black mate finish. Front of the device have one 3.5mm SE jack and a 4.4mm gold plated balanced jack. The back have a USB-C connector. Left side of the body have a metal gain switch. Everything feel well crafted.

You can buy a leather protective case for 25$. In all honnesty, at 250$, i would have expect it to be include in accessories, which include 1 basic USB-C, one USB-C cable and one USB-C to USB cable and a USB-C to lightning cable . It doesn’t include USB-C to lightning cable, another potential extra cost for Iphone user.

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Packaging is minimal, nothing really to write about and as noted, inclusion of a protective case would have been very welcome.

Lastly, about this protective case, i’m not sure of it’s exact purpose apart adding a classy touch to the M15, since the glass isn’t protected and will still be prompt to scratch or perhaps breaking if drop on the hard floor.

AMPLIFICATION​

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High gain 4.4mm: 72.72mW@32ohm – 1.525Vrms- THD+N=0.00139% Impedance= 1.22ohm

High gain 3.5mm: 42.25mW@32ohm -1.163Vrms- THD+N=0.00084% Impedance=0.96ohm


Compared to several portable dongles delivering 4vrms in balanced mode, the M15 may seem very limited with its 1.525Vrms in high gain balanced mode, fortunately this does not translate into impressions of loss of volume or dynamics because even the Sennheiser HD820 can sound full, open and loud with their 300ohm.

So, with my tests, I would conclude that this type of power limitation will be more problematic for earphones or headphones with low sensitivity than low or high impedance with normal or high sensitivity. For example, the Final E5000 have an impedance of only 14ohm but a very low sensitivity of 93ohm, which seems to conflict with the type of amplification of the M15 by not allowing the transducer to act correctly, which creates invasive distortion and compressed sound. This case of the E5000s is an exception and no other IEM or headphones have suffered this tragic fate.
Despite an output impedance that may seem high for very sensitive or low impedance IEMs, the rendering of M15 remains clean, balanced and without distortion for sensitive IEM, as the Audiosense T800 (9ohm) and Dunu DK2001 (110db-32ohm) proved it.
So my advice here would be to avoid earphones or headphones with very low sensitivity and maybe opt for an impedance of 16ohm and above to be safe. The M15 will have no difficulty correctly driving 99% of theIEM, earbuds and headphones on the market, with a power well felt in its dynamics and without distortion or invasive hiss.


The current mode amping technology used by Questyle is nothing like voltage amplifier using OPamp for extra gain.

''Current Mode Amplification features the use of transistors to amplify and a fully discrete structure, to wit: voltage input and output, while the core amplification takes place in the current domain operating in a pure Class A state. It is completely different from the traditional voltage mode amplifier in the structure of the amplification circuit. Current-mode audio amplifiers affect the speed and bandwidth of the transistor-level capacitance between the low impedance nodes, not only completely eliminates the transient intermodulation distortion (TIMD), but can easily attain ultra-high bandwidth (full power bandwidth of 500kHz ) and ultra-low distortion (lower than 0.0002% THD+N, challenging the physical limits of audio testing). The Current Mode Amplification technology can be used for amplifiers of any power level (10mW-2000W) and of any size (thousands of square centimeters for some professorial amplifiers).''


But how does it translate in sound perception? Well, imagine a THX AAA amplifier, like SMSL SH9, but with greater dynamic impact and denser more natural timbre, and your not far from M15 amping experience. Current drive seem to deliver power in a different way too, resulting in louder sound than it's 75mw suggest. I'm not sure to know how to explain this, but the fact it was able to drive correctly and without distortion or compression in dynamic the Sennheiser HD820 is sure impressive.



SOUND IMPRESSIONS​

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TONALITY

A neutral rendering but not flat in dynamics which it approaches more the W shape with an injection of weight and density in the low, medium and high. Everything in timbral and tonal balance is natural and cohesive. It’s not colored while being not clinical or cold in the rendering too, it borders on the analytical without having any spike or imbalance in the rendering of the frequencies which would harm the cohesion of the whole. It’s crisp yet well rounded balance.
Still, the widest frequency band is the highs and the M15 keeps this in focus, preserving its fullness of rendering and cleanliness of presence. In my opinion, here we are in the best of worlds where romantic musicality and a high degree of technical performance meet and embrace each other in complete naturalness.



RESOLUTION & PRECISION

With the M15, we are not in warm or dark territory, nor in artificial amplification of clarity, certainly the resolution is very high and will make you discover new details in the music you listen to, but without pushing them forward with aggressiveness or too much amplification of the texture to make their presence stand out.

Here, Questyle has drawn the full potential of its saber ES9281 DAC thanks to a clean, linear and varied amplification in its dynamics. Macro-resolution is favored here, it’s vast and detailed, transparent and revealing. The sound layers cut across spatiality while keeping intact the well-defined presence of static elements. The definition of micro details is between analytical and softened neutrality, which somewhat polishes the sibilance of aggressive IEMs like the Final A8000s, and also densifies the timbre a bit. I wouldn’t say that the noise floor is 100% black, because the silence between instruments is a little vibrant, but it’s not far from it, especially when using IEMs and headsets not intensely sensitive to output impedance.

The precision is very high with the M15, even in fast and complex passages the rendering is very articulate and defined in the separation of its attack. But the M15 has a slightly rounded sound at each end, so the sub-bass will be a little more difficult to pin down or feel, and the very high frequencies will not be perfectly sculpted.
Being familiar with this ES9281 DAC, I can confirm that the M15 pushes its technical performance to its peak, including its level of resolution, transparency and definition of these micro-details.



DYNAMIC

One of the most difficult aspects to describe is the dynamic rendering of an audio source, which is often more dependent on its type of amplification than on the decoder itself. Here, I feared that the M15 rendering would be too flat and linear, similar to a THX amp, and thank God, this is not the case at all! We are in the best of worlds with the M15, which balances between attack speed and resolving capacity with a desire for musicality well felt in the heaviness of impact and the reliefs of diversified attack amplitudes. The impact of the notes has weight, the piano does not sound flat. The mid-bass hits hard, with a nicely sculpted roundness. The high frequencies are incisive in the attack and restore as much in their body and harmonic presence. This dynamic doesn’t create much resonance after impact, which is good for bass impact and also midrange control, but a bit less for more airiness and echoing super high-frequency brilliance. .

OTHER TECHNICALITIES

The spatial presentation is well balanced between width and depth of scene, and also very realistic. It doesn’t sound closed, it’s circular and full, with no presence hole. It’s wide and reasonably deep but won’t enlarge your headphones’ stage unduly. What matters here is that it doesn’t compress the rendering or affect its accuracy, which is fully the case with the M15. The sound imagery is really impressive, without artifice we have a natural separation of the moving sound layers and enough well-defined space between the static instruments. It’s not analytical but naturally revealing, even I would say that the entire sound spectrum is treated in the same way, so no micro high details better separated than the rest accentuating an impression of air and space. As for PRaT (Pace, rhythm and timing), it’s excellent here and proof that we have a mid-range DAC-AMP of high quality and fidelity. The M15 will never muffle or distort excited passages of speedy busy music and deliver sharp timing into full articulation regardless of the attack speed.
The density of timbre is amplified by the longer sustain of the notes than their impact resonance time, so no, the micro separation of each note playing at crazy speeds will not be magnified or shadowed by a mixture of impact resonances.
Attack sustain-release is central to precision, accuracy and attack speed definition. Here, the M15 is not 100% perfect and my SMSL SU-9+SH9 stack is cleaner and more precise in sustaining and detonating sounds. Still, the M15 is superior to all my other DAC-AMPs at this level, including the Tri TK2 and Xduoo Link2 Bal, which have more harmonic distortion and impasto when I play the frenzied jazz rock album ”Dodovoodoo” by Elephant9.

COMPARISONS​

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VS XDUOO Link2 Bal (dual cs43131+independent Opamp-270mw@32ohmbal-160$)

There are two big acoustic differences that strike the informed listener when comparing these two excellent DAC-AMPs, these are the wider stage width and height of the Xduoo as well as its warmer resolution and less clear and precise than the M15. Immediately, the technical performances of the M15 seem higher, both in the control, the synchronicity, the speed and precision of the counterpoints of the attacks and the cleanliness of resolution in the macro and microscopic sense. The M15 is more neutral, less colored by warmer, looser and boosted bass. This may make its dynamics seem weaker and limited in amplitude power, but this is not the case if we compare the treble rendering which is more pushed and extended, delivering and extracting micro details with greater ease, this which is evident in fast and complex passages of music, where the Xduoo will show some limitation in terms of saturation and distortion, both higher than the M15. Xduoo has a warmer, analogous and fleshy tonality, with thicker and opaque sound layers, it favors relief more than the texture of the timbre and its transparency than the M15. Its highs shimmer less and get lost more in its fluffy sonic ensemble. M15, without being cold or clinical, delivers less soft and rounder basses in their impact, and a more precise, articulated instrumental separation without adding color. The Xduoo remains a superior DAC-AMP in terms of construction and tactility, having a volume control, a gain switch and even UAC 1.0 and 2.0 selection switch, but above all a chassis that seems extremely durable compared to the pretty body of the M15 which has a glass certainly interesting for the eyes but worrying for the durability. In the end, the M15 offers a more neutral and detailed tone with superior technical performance and slightly less powerfull amplification to the Xduoo Link2 Bal.

VS TRI TK2 (dual ES9038q2m+A\B amp-1250mw@32ohm-280$)

What strikes the listener in the first place is how the spatiality is wider, grand and open as well as the dynamics more corpulent and heavy in impact. The general resolution is more subdued and not as clean with the TK2, without being dark, only less precise and cut in its separation and less clear in the definition of each instrument. The M15 is more neutral and analytical, with a thinner and more textured timbre, better transparency but a more closed and condensed scene. The bass is more colorful with the TK2, warmer and boosted with a less defined but more resonant hit, which tends to make the transition with the mids more veiled and organic. Here, the M15 does not force the bass overflow into the mids and keeps the separation clear while delivering a more energy-focused and resonantly controlled strike. The mids seem a bit flatter and set back with the M15, but more centered and less diffuse in their separation. High frequencies are drier, clearer and more textured with the M15, delivering more energetic and fully rendered percussion. The TK2 is about 5 times bigger and heavier than the M15, it is not really portable and its gain is triggered when you pass a certain volume level, I would have preferred a switch like the M15. Technically speaking, I would conclude that the M15 is superior due to a darker noise floor, higher resolution, more precise instrument separation as well as a more controlled and less diffuse attack, however I tend to prefer the warmer, natural and open tone of the TK2 because the instruments have more body and a wider and creamier projection, but my conclusion in terms of musicality might be different with less aggressive IEMs than the A8000.

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VS Xduoo Poke II (dual CS43198 dac-700mw-390$)

Another excellent DAC-AMP using current amplification, but this time with an ES9281C saber DAC. Also, without battery and with supposedly lower amplification force although more energetic in its dynamics. Here, the M15 delivers meatier, vibrant and warm bass with more pronounced impact heaviness. The resolution is almost identical, although less finicky in the micro-definition, favoring a roundness of tone denser than the Poke II. In terms of precision and separation, the Poke is an iota superior because it is clearer and cleaner with a more restrained attack in its echo. The M15 has a spatial rendering that has more relief and sculpture of presence, giving a more holographic and open effect in height and width. The spatiality of the Poke is deeper with more static instrumental positioning, more defined and focused in the high frequencies. The flatter, more clinical rendering of the Poke tends to be less immersive and encompassing for the listener than the M15, which despite a technical performance of high resolution and a bit lower micro-details, delivers a more natural, physical and tonally accurate musicality.

PAIRING​

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With the FINAL A8000

These exceptional intras are my reference no1 because the presence of all the frequencies is fleshy, dynamic, clear and precise, nothing is behind and despite a few points in the bass, midrange and high, the balance is intended to be energetically neutral. . With an overly aggressive DAC-AMP, the A8000s can scream a bit and the M15 doesn’t cause this while preserving their high resolution and dynamic energy. The first thing I notice is that the basses are more textured and transparent, preserving their heaviness of impact without boosting their resonance. The sub-bass is not pushed back or attenuated and vibrates naturally without taking over the mids with a surplus of presence. The mids are less prone to sibilance than with a FIIO KA3, but don’t gain much body, it remains fairly centered with high clarity and good separation. It’s not compressed but not very open either. The highs gain in fullness of timbre but not in brilliance or resonance In terms of spatiality, it gains in depth while maintaining an average width and height. The instrumental separation is not negatively impacted but does not gain space. Let’s say that the A8000s remain faithful to their deep nature with the M15, without added color, their tone or timbre is not boosted any further, and their technical performance is accentuated in controlling their extremely fast attack. Still, I would have preferred a little more addition in terms of dynamics and also the presence of bass.

With UM Mext

These two seem to be made to go together, the presentation here is so beautifully balanced, corpulent in dynamics and highly resolute. MEXT basses gain in roundness, texture and immediacy of impact. The mids are superbly resolved, clear, transparent without grain but nuanced in texture, here it’s open and frontal, it seems that the bone conduction driver appreciates the amplification while running, it’s clean, wide of stage and natural , truly breathtaking. And what about the highs, again a similar treatment, but less thin and shiny than with some other dongles like the Tempotec E44. The amount of sound information is infinite but transmitted delicately, and once again, the completely black background accentuates the cleanliness of the space, improving the resolving complexity and instrumental separation as well as the depth of the scene. Truly, if you’ve owned MEXTs and are looking for the perfect dongle to do them justice, the Questyle M15 is its soul mate.

With MOONDROP ARIA

I would have thought that this pairing would be perfect, but it’s not exactly that…here we have clearer and more aggressive Arias, with more emphasis on texture and dry tone. The bass, which was already lacking a bit of well-felt punch, does not gain any advantage, although the kick drum has more texture and a gripping presence, and it seems that the sub-bass extends and vibrates less too. The mids are less organic, leaner and drier, with a flatter presence and less open projection. The highs gain in texture and grip, suddenly the electric guitar sounds surprisingly good, with a rich and transparent distortion, more bite in the attack, something that was often missing with other dongles such as Tri TK2, Xduoo Link2 Bal, but what is strange is that the body remains thin, so the guitar lines do not have this heaviness and immediacy of presence.

With the FINAL E5000

Here we have IEMs known to be difficult to drive correctly and I will be short because indeed the E5000 creates a disaster with the M15. I was expecting a little compressed sound but here it’s distortion problems with the bass that ruin the listening. But not only. The transducer really doesn’t seem to like the current type of amplification and I don’t know how to explain this. The entire dynamic becomes distorted at the slightest increase in diversified amplitude mixing different frequency spectra. At low volumes, this won’t be as problematic, but the E5000s will sound flat in dynamics, compressed in image and too emphatic in the highs. If you plan to use M15 for the Final E5000, I strongly advise against it.

With the Audiosense T800

Let’s start by saying that the T800s are sensitive to the amplification impedance and the M15 is not the lowest on this side (more or less 1ohm). Fortunately, this does not result in extreme distortion, although sometimes present at high volume, especially with high gain. At low gain, the rendering is tonally linear and dynamically energetic. The bass is more textured and less boomy and resonant, which accentuates the clarity of the T800s and makes them more balanced neutral because the highs are not amplified. The vocals are less prompt to sibilance and a little less open in width. I would say that the T800 loses cleanliness and analytical clarity in more complex passages, which does not happen with a lower impedance source like the Xduoo X20 or Ibasso DX90 (0.1ohm).

CONCLUSION​

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In the last years, i’ve been spoil with alot of great sounding dongles, ranging from 20$ to 500$. Lot of them were redundant too and not that much of a big sound upgrade in the 20 or more I try or own. So, I learn exceptional sounding DAC-AMP are rare when it come to plain sound quality.

Here, with the M15 we are in mid-costy territory, so my expectation were very high. To conclude that it offer high sound value mean it’s able to compete with pricier DAP or DAC-AMP in sound quality, and thanks to the magic of current mode amplification as well as good DAC implementation of Questyle, this DAC-AMP deliver a sound quality that fit or even surpass it’s price tag. It’s literally end game dongle for everything but perhaps end game amping power.

The M15 might be the only ”reference” ultra portable DAC-AMP out there, in the sens that it deliver an high fidelity neutral sound with heavy dynamic heft and natural yet crisp resolution. This high end dongle know how to sign and dance, it have enough power output for majority of IEM and Headphones while not being hungry for your phone battery life, and hey, it show you it’s geeky soul under the glass of it’s body too!

Highly recommended!

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PS: I want to thanks Questyle for sending me this review unit and answering all my questions too. It was a very pleasant communication, very generous, transparent and informative. I'm not affiliated to this nice company and share my 100% independant honnest audio impressions as always.


You can buy the Questyle M15 for 250$ from this official seller: https://www.linsoul.com/products/questyle-m15?variant=42702297497817

For more honnest and diversify audio reviews, give a look to my No Borders Audiophile website
HERE.
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OhmsClaw
OhmsClaw
@klaus2325 why wouldn't a current amplified dongle be a great pair with low impedance planars? Also if it's the dream pairing with the MEXT, the Rai Pentas are essentially that. If stated OI is <1Ohm its unit variation for the money but still entirely negligible with regard to down sloping response or BA loading.
klaus2325
klaus2325
Thanlks for your kind answers. I´ve totally misunderstood something. Sorry for my "silly" question
NymPHONOmaniac
NymPHONOmaniac
@klaus2325 i didnt try those iem-hp but indeed, M15 can be imprevisible in some rare case like with E5000 i write about in this review. I wouldn't suggest M15 for very capricious or sensitive IEM nor for very power hungrry headphones as an end game source. Especially low sensitivity db one.
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