Questyle M15 · Mobile Lossless Headphone Amp with DAC

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.

IMG_20220811_105313.jpgIMG_20220811_105344.jpg


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.
Last edited:
  • Like
Reactions: RemedyMusic

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!

1657618618027.png

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.

1657623866393.png



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.

1657624356635.png


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.

1657625663875.png



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.
1657624985350.png

1657625025467.png

1657625060075.png


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.
1657626378610.png


1657625271075.png

1657625320837.png

1657625373545.png

1657625402211.png


1657625731397.png




NOW LET'S TALK ABOUT THE SOUND....
1657625769403.png

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

1657626114161.png

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


1657626171542.png


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.
1657627063357.png

1657627164790.png


Comparisons:
1657627612529.png


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

1657627655837.png

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.

1657628383228.png

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.

1657629246698.png


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..
Last edited:
asifur
asifur
@Elim Garak if you like the analogue R2R tonality go for RU6.
Otherwise, better to go with M15.
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.

BonGoBiLai

New 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.

IMG-3640.jpg


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).

IMG-3647.jpg


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

00000IMG_00000_BURST20220529234325379_COVER.jpg


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


289961223_1019548702032841_8669830287569722213_n.jpg


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

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

c6Bnfi2smkSoWc4lG2HNYvA4FlXAmLGGvReMCmZV9zQLmo9z__h1k-6R8kcHhXr74BIlm-OWbnB3hjiNc4bz36lc-ckXyvoPx5h-ZTXBbS22fNImLiR9zc-YxJE5UxARMO0GSk99OWg3yZ2bMQ


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 )
c-MgG6mWosWJITTcpuVY0ZrH6wrpFiBbnAyWAYlXxWWu7Ildauz7u0XKkMrwAGqopV-cbcfZylDN6QbeqftIrRnzNQWmPi0mKyzkyCQlmhtjqqiRad785gspNo1pnkUQ_MWgmLWHJUYiI8SBkg

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.

8VyJwcKUgvWEH_0bFWrWF_kI6mb8IXZwZXbMuuSMgONljhhestWMSe7sKI7KeVhirtWyznlxnaHy2BN65fuXJziw1UJm9eubgFjtUeWgW1O3b6zJQhZKGy_SmR7rsQ17Auu1r6_Rz2rYTaR9xQ


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.

1655916051702.jpeg


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

1655916073021.jpeg

Attachments

  • 1655916071925.jpeg
    1655916071925.jpeg
    4.8 MB · Views: 0
Last edited:

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
image-14.png



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?

image-13.png
image-12.png


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.

image-9.png
image-15.png

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.

image-10.png



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.

image-11.png

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​

image-19.png

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​

image-16.png

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​

image-7.png

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.

image-8.png

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​

image-18.png

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​

image-20.png

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!

-------



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.
Last edited:
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.

Moonstar

100+ Head-Fier
Questyle M15 USB DAC/Amplifier Review
Pros: Overall Clarity, Resolution and Authority,
Very Balanced & Natural Sound Profile,
Both 4.4mm Balanced & 3.5mm Single Ended Outputs,
Ultra Clean Output that is Ideal for Sensitive IEM’s,
Powerful Output for power hungry Headphones,
MQA & Native DSD Support up to DSD256,
Stylish Design & Premium Build Quality
Cons: No Physical Buttons for Volume Adjustment,
No Protective Case or Lightning Cable included to the Package (The Leather Case is available for FREE for a limited Time)

Questyle M15 Ultra Portable USB DAC/Amplifier Review


20220506_182943-01-neu-scaled.jpeg



Introduction:

Questyle Audio is a Chinese company that is specialized in research of high-tech lossless audio system such like Desktop Amplifiers (CMA800/CMA800R), DAC/Amplifiers (CMA Twelve, CMA Fifteen, CMA 400i), Wireless Audio Systems, Portable DAC’s (M12) and Audio Players (QPM, QP2R). Questyle has won over 20 international awards since 2015, such as CES Innovation Award, iF Industrial Design Award, and VGP Lifestyle Award, while Foxconn Technology Group is a strategic partner of the company.

The Questyle M15 that I will now review for you is the company’s flagship ultra portable USB DAC/Amplifier that features a ESS ES9281AC DAC Chip, TOREX High-Efficiency Power Management Unit and both 3.5mm Single Ended and 4.4mm Balanced Analog outputs. Moreover, the M15 contains two of Questyle’s patented CMA (Current Mode Amplification) SiP modules, for a total of four CMA AMP engines to driver both Sensitive IEM’s and demanding headphones as well.


20220507_144516-01-scaled.jpeg






Disclaimer:

I would like to thank Questyle for providing me the M15 Ultra Portable USB DAC/Amplifier as review sample. I am not affiliated with Questyle beyond this review and these words reflect my true and unaltered opinions about the product!





Price & Availability:


The actual MSRP price of the Questyle M15 USB DAC/Amplifier is 249.00 US$. More information’s can be found under the link below;





Package and Accessories:

The Questyle M15 came in a relative small rectangular back cardboard box with a premium look and feel that sports some product related brandings o the top and specifications at the bottom.

20220506_182027-scaled.jpg
20220506_182035-scaled.jpg




Inside the box are the following contents & accessories;

  • 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)


20220506_182053.jpg
20220506_182347-scaled.jpg




The M15 has a premium looking leather case available in 3 different colour options that is sold separately for 30.00 US$. The good news is that you can get now for FREE for as Launch Gift for a limited time (till 15th of May).

M15-GIFT.jpg


20220523_190843-scaled.jpg


20220523_190932-scaled.jpg
20220523_190937-scaled.jpg
20220523_191004-scaled.jpg
20220523_191008-scaled.jpg
20220523_191433-scaled.jpg








Design & Build Quality:

The Questyle M15 is an amazing looking USB DAC/Amplifier that offers a unique visual experience with its CNC machined aluminium housing with a transparent top cover, which feels very premium and robust when you hold it in your hands.

20220506_185015-scaled.jpg


The M15 is an Ultra Portable USB DAC/Amplifier with dimension of approx. 61.8[L] X 27.2[W] X 12[D]mm without the low profile cables that are included inside the package.

20220506_182402-scaled.jpg


The main body that is made from CNC Machined Aluminium alloy material is in black colour and shows a rectangular shape with slightly rounded edges.

20220506_183107-01-scaled.jpeg


At the left surface of the M15 is the Low & High hardware switch that I do prefer over software controlled gain options.

20220506_183040-01-scaled.jpeg


At the right surface of the device is the “M15 Mobile Lossless DAC with Headphone Amplifier” branding.

20220506_182943-01-neu-scaled.jpeg


On the top of the M15 is a transparent top cover that makes it possible to see the PCB layout with all the hardware components like the ESS ES9281AC DAC Chip, TOREX Power Management Unit, SiP Current Mode Amplification modules, 4.4mm Balanced and 3.5mm Single Ended output and more, which offer visually attractive experience.

20220506_183127-01-scaled.jpeg


Here are also two LED light indicators, one is dedicated for the gain status (red & green) and the other one is the Data Indicator that gives information about the actual payed format.

20220506_183731-scaled.jpg


On the top of the device are both the 3.5mm Single Ended (with CTIA support for headphones featuring phone calls) and the 4.4mm Balanced (TRRRS “Pentaconn”) headphone outputs that do offer a tight and sturdy connection.

20220506_183022-02-01-scaled.jpeg


The rear surface of the M15 ultra-portable USB DAC/Amplifier features the Questyle logo/branding.

20220506_182834-01-scaled.jpeg


On the top of the device is the USB Type-C DATA port that is dedicated for the digital data transfer.

20220506_182953-01-scaled.jpg


The overall build quality of the Questyle M15 and the cables is of high quality that fulfils my expectations from an audio gear at this price level.

20220506_183428-01-scaled.jpeg








Technical Specifications:


  • DAC chip : ESS ES9281AC
  • Frequency Response : ±0.1dB (20Hz-20kHz)
  • THD+N : 0.0003%
  • SNR : -130dB
  • Output power : 3.5mm: 11.97mW @300Ω, 4.4mm: 22.60mW @ 300Ω
  • PCM : up to 384kHz (16/24/32Bit)
  • DSD : up to Native DSD256 (1Bit 11.2MHz)
  • Dimension : 61.8[L] x 27.2[W] x12[D] mm




M15.png








Hardware & Software Features:


The Questyle M15 is an Ultra-Portable USB DAC/Amplifier that offers some impressive hardware specs such like the ESS ES9281AC DAC Chip, TOREX High-Efficiency Power Management Unit and two of Questyle’s patented CMA (Current Mode Amplification) SiP modules.



A) DAC (Digital to Analog Converter):

The M15 features ESS Technologies ES9281AC flagship DAC Chip, which is a feature rich 32bit 2-Channel Digital to Analog Converter that utilizes the critical acclaimed ESS patented HyperStream II architecture. The device offers an impressive SNR (Signal to Noise Ratio) of -130dB and a decent THD+N (Total Harmonic Distortion) of only 0.0003%.

The Questyle M15 support sampling rates from 16, 24, 32Bit, 44.1, 48, 88.2, 96, 176.4, 192, 352.8, 384kHz and up to Native DSD 256 (1Bit 11.2MHz).

The LED Indicator that is visible under the transparent front panel of the M15 gives information’s about the data status, which are list below;

  • Green: Sample rate is 48kHz or less.
  • Red: Hi-RES lossless files up to PCM 88.2kHz~384 kHz & Native DSD64~DSD256.
  • Magenta: The M15 is performing the final unfold of an MQA Core stream.


20220506_183731-scaled.jpg




B) Connectivity:

Inside the box are two low profile USB cables, one USB Type-C to USB Type-C and one Type-A to USB Type-C cable to connect the M15 to your Digital Music source.

Devices offers a plug and play function that supports Android 5.0 and above, Apple iOS devices such like iPhone and iPad, Windows PC’s with Win10 1803 and above, and Apple computer with MAC OS.

20220506_182410-scaled.jpg




C) Amplification & Background Noise:

The Questyle M15 is a very powerful device especially for an Ultra-Portable USB DAC/Amplifier thanks to the use of its patented SiP modules, for a total of four CMA AMP engines. This quadruple drive amplification circuitry gives enough out power to drive even high demanding planar headphones such like the HiFiMAN Sundara or SIVGA P-II.

20220515_195127-scaled.jpg


Questyle’s Current Mode Amplifiers are characterized by their small footprint, low voltage operation, and minimal power consumption. Current Mode amplification offers also a low impedance (according to Questyle that is not listed on their specs), a bandwidth up to 1MHz and a Total Harmonic Distortion of 0.0003%.

Here are some Technical specs about the output power of the Questyle M15:

  • 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%
What I really like and immediately noticed on my first listen to the M15 was the ultra-clean and dark background that allows you to hear and to discover even the smallest micro details, which is quite impressive for a device with such a small footprint.



20220506_184125-01-scaled.jpg




D) Power Consumption & Overheating Performance:

The Questyle M15 is equipped with the TOREX High-Efficiency Power Management Unit to archive a relative low power consumption to increase the battery life of your source, which was quite decent compared to other USB DAC/Amplifiers that I have used before, especially with such a powerful amplification capability.

What I also found quite impressive is the that the Questyle M15 doesn’t overheats after long listening periods, even while powering some of my high demanding full sized open-back planar headphones such like HiFiMAN Sundara or SIVGA P-II.







Equipment’s used for this review:


  • DAC/Amplifiers : Questyle M15, Cayin RU6, Shanling UA5
  • USB Source : Samsung Galaxy Note10 Plus, Asus TUF FX505DU
  • IEM’s : Meze Audio RAI Penta, Campfire Audio ARA, Kinera URD
  • Headphones : SIVGA P-II, HiFiMAN Edition XS, HiFiMAN Sunadra


20220506_184308-scaled.jpg








Albums & tracks used for this review:


  • Adele – My Little Love (Spotify)
  • Randy Crawford – On Day I Will Fly Away (Flac 16bit/44.1kHz)
  • Hayley Westenra – Odyssey Album (Dezzer HiFi)
  • Dionne Warwick – Walk On By (Flac 16bit/44.1kHz)
  • Sarah McLachlan – Angel (Flac 24bit/48kHz)
  • Sertap Erener – Aşk (Flac 16bit/44.1kHz)
  • Sonya Yoncheva – (Giuseppe Verdi) II Trovatore, ActI (Flac 24bit/44kHz)
  • Edith Piaf – Non Je Ne Regrette Rien (Flac 16bit/44.1kHz)
  • Diana Krall – So Wonderful (DSF)
  • Aretha Franklin – I Say A Little Payer (Flac 24bit/96kHz)
  • David Bowie – Heroes (Flac 24bit/192kHz)
  • Elton John – Rocket Man ((Flac 24bit/96kHz)
  • Barry White – Just The Way You Are (Flac 24bit/48kHz)
  • Isaac Hayes – Walk On By (Flac 16bit/44.1kHz)
  • Sting – Englishman in New York – (Flac 24bit/48kHz)
  • Eric Clapton – Wonderful Tonight (Flac 24bit/96kHz)
  • B.B. King – Riding With The King (Tidal Hi-Fi)
  • Dave Gahan – Kingdom (Tidal Hi-Fi)
  • U2 – Sunday Bloody Sunday (Flac 16bit/44.1kHz)
  • Bro Safari, UFO! – Drama (Deezer HiFi)
  • Armin Van Buuren – Vini Vici (Flac 16bit/44.1kHz)
  • Really Slow Motion – Deadwood (Deezer HiFi)
  • Massive Attack – Angel (Flac 24bit/192kHz)
  • Lorde – Royal (Flac 24bit/48kHz)
  • Toutant – Rebirth (Deezer HiFi)
  • Gogo Penguin – Raven (Flac 24bit/192kHz)
  • Portishead – It Could Be Sweet (Spotify)
  • Charly Antolini – Duwadjuwandadu (Flac 24bit/192kHz)
  • Michael Jackson – Billie Jean (Flac 24bit/192kHz)
  • Ferit Odman – Look, Stop & Listen (Flac 24bit/192kHz)
  • Chopin – Nocturn No. 20 In C-Sharp Minor (Flac 16bit/44.1kHz)
  • Fazıl Say – Nazım Oratoryosu (Live) (Flac 16bit/44.1kHz)
  • Vivaldi – Le QuarttroStagioni “The Four Season” (Deezer HiFi)
  • Otto Liebert& Luna Negra – The River (Flac 24bit/192kHz)
  • Lunatic Soul – The Passage (Flac 16bit/44.1kHz)
  • Deftones – My Own Summer (Shove it) (Flac 16bit/44.1kHz)
  • Photek – The Hiden Camera (Spotify)
  • Muse – Hysteria (Flac 24bit/48kHz)
  • Metallica – Sad but True (Flac 24bit/96kHz)
  • Opeth – Windowpane (Flac 16bit/44.1kHz)
  • Megadeth – Sweating Bullets (Tidal Hi-Fi)
  • Rush – YYZ (Flac 16bit/44.1kHz)
  • Rush – Leave That Thing Alone (Flac 16bit/44.1kHz)
  • Slayer – Angel of Death (Spotify)
  • Liquid Tension Experiment 2 – Acid Rain (Spotify)
  • Yosi Horikawa – Bubbles (Spotify)








The Sound:

The Questyle M15 immediately impressed me with is very natural, pretty organic, balanced and highly transparent overall sound presentation, which also benefits from an ultra-clean & pitch-black background that creates an atmosphere where you can hear even the smallest micro details.

This review has been written after a burn-in period of approx. 80 Hours. I have paired the Questyle M15 with sources like the Samsung Galaxy Note10 Plus and the Asus TUF FX505DU PC. My sound impressions below are mainly based on my experiences over the 4.4mm Balanced output paired with the Campfire Audio ARA, Kinera URD, Meze Audio RAI Penta IEM’s and HiFiMAN Edition XS and SIVGA P-II headphones.

20220506_183546-01-scaled.jpeg




Bass:

The Questyle M15 offers a very natural and balanced bass response along with a decent grade of technical performance. The general bass character of the M15 can be described as highly controlled and quite detailed, from the subbass up to the midbass area.

The subbass region of the M15 reaches pretty low and offers a good sense of rumble and control paired with IEM’s like the Kinera URD or Meze Audio RAI Penta when I do listen to songs like Bro Safari, UFO’s “Drama“, Lorde’s “Royals” or Massive Attack’s “Angel”.

The midbass region is one of the highlights of this ultra-portable DAC/Amplifier that is reproduced with great sense of impact, clarity and authority when I do listen to complex passages Charly Antolini’s “Duwadjuwandadu” or Gogo Penguin’s “Raven”.

Instruments from cellos to bass guitars do have a good level of weight and fullness, while snare and kick drums are represented in a pretty tight and impactful manner when I have listen to the Questyle M15 with high-end In-Ear Monitors like the Campfire Audio ARA and Meze RAI Penta.

20220515_194948-scaled.jpg




Midrange:

The Questyle M15 shows a very natural, liquid and highly transparent midrange presentation with decent sense of airiness and headroom for instruments and vocals. The general tonality of the midrange is a tad warmer than neutral and pretty organic, which is one of the highlights of this small USB DAC/Amplifier.

The lower midrange of the Questyle M15 offers a pretty good sense of body and depth when I do listen to male vocals like Barry White, Elton John, Dave Gahan or David Bowie or to instruments like acoustic guitars, violas or trumpets. The upper midrange region is another highlight of the Questyle M15 that is reproduced in a quite detailed, dynamic yet controlled manner. Female vocals from Adel to Sarah McLachlan, Edith Piaf to Randy Crawford do sound lively, fluid and emotional, especially when I pair it with IEM’s like the Kinera URD, Meze Audio RAI Penta and HiFiMAN Edition XS headphone.

Instruments on the other hand do have a pretty natural timbre and are shown in highly detailed and well extending manner that surpassed my expectation from such a small and well-priced product. What also surprised me was the sense authority when I have listen to guitar solos with high level of distortion such like Megadeth’s “Sweating Bullets”, Slayer’s “Angel of Deaths” or to Rush’s “Leave That Thing Alone”.

20220506_184500-scaled.jpg




Treble:

The treble range of the Questyle M15 is fluid, highly controlled and detailed. It offers a decent sense of presence and brilliance when I do listen to instruments and soprano voices. The transitions in moment when instruments do play with high level of distortion are reproduced in a quite controlled manner with all IEM’s and headphones that I have listen to it, which is quite surprising for a devices that is equipped with a ESS Sabre DAC. This shows how well the sound engineers have implemented an ESS Saber DAC that sounds both detailed yet controlled in this area.

The lower treble range of the M15 adds to the overall presentation a decent level of clarity, while the extension is pretty successful while listen to instruments like snare drums or cymbals and soprano voices like Sertap Erener and Sonya Yoncheva.

The upper treble region is able to produce a pretty good level of airiness and sparkle when I do listen to instruments such like pianos, hi-hats or cymbals, especially when paired with the Campfire Audio ARA, SIVGA P-II and HiFiMAN Editions XS.

The overall control, extension and detail retrieval of the Questyle M15 is simply stunning, while the intensity and quantity in this area is not too much or too low, which makes it to a very versatile source.

20220506_183428-01-scaled.jpeg




Soundstage & Imaging:

The Questyle M15 has a fairly spacious and airy soundstage atmosphere that is suitable for a precise placement and separation of instruments and vocals. The soundstage of the M15 shows an efficient level of depth and wideness that is not spectacular but sufficient for such an Ultra-Portable USB DAC/Amplifier device.







Comparisons:




Questyle M15 versus Cayin RU6:

The Cayin RU6 is one of the popular Ultra-Portable USB DAC/Amplifiers on the market that gained attention with its discrete R-2R DAC circuit design and powerful output capabilities for its size.

When it comes to the build quality, I can say that both products do offer a premium look and feel. The Cayin RU6 is slightly thicker and longer with dimension of 65×25.4×13.7mm, while the Questyle M15 is a bit slimmer and a bit wider with about 61.8×27.2x12mm. The RU6 has a small OLED screen that gives information about the sampling rate, volume, etc. and comes with physical hardware buttons that are dedicated for volume and mode selection. The M15 on the other hand has no screen or buttons for volume control, but comes with LED light indicators that do give information’s about the sampling and gain status, and is also equipped with a Low/High gain switch that the RU6 not has.

20220515_200942-scaled.jpg


Both devices do offer both 4.4mm Balanced and 3.5mm Single ended outputs. The Cayin RU6 is equipped with its own 24-bit R-2R DAC design, while the Questyle M15 features the ESS ES9281AC DAC Chip. Both are capable to decode Native DSD up to DSD256 and PCM 24 bit/384kHz, while the M15 supports also MQA. The RU6 and the M15 are able to driver full sized open-back planar headphones such like the SIVGA P-II or HiFiMAN Sundara/Edition XS, while the Questyle M15 seems to be even more powerful than the Cayin RU6 especially on high gain. What I don’t like about the analog outputs of the RU6 is that there is an audible background noise, while the M15 is death silent. The EMI shielding of the RU6 seems not to be the best, since it has picks up some interference from my Samsung Galaxy Note 10 Plus, when I put them side by side.

20220515_200212-01-scaled.jpeg


As for the sound, I can say that both devices offer different flavours that can be preferred to each other. The Cayin RU6 shows a slightly warmer tonality that is close to the classical analog sound signature, while the difference is not very high. The Questyle M15 seems to be slightly more neutral in tonality, but has also a pretty organic timbre.

Both the subbass and the midbass region of the Cayin RU6 do show slightly more depth and intensity compared to those of the Questyle M15. However, the M15 has the upper hand in terms when it comes to the clarity, resolution and sense of authority in the lower frequency register.

The midrange of the Cayin RU6 has a pretty warm tonality and highly musical character that I really enjoy. The Questyle M15 on the other hand shows a slightly more natural, neutral and somewhat organic timbre when I do listen to both vocals and instruments. The M15 offers a higher sense of transparency and airiness in this area. The lower midrange of the RU6 shows a bit more body and depth, while the M15 has the slightly edge when it comes to the clarity and resolution in this register.

The upper midrange and the treble region of the Questyle M15 sounds slightly more highlighted and energetic/dynamic compared to those of the Cayin RU6, without to be overly sharp or sibilant. The treble region of both devices sounds in general pretty controlled, while the M15 has the slightly edge when it comes to the level of resolution, extension and separation that was quite audible when I do listen to instruments like cymbals or hi-hats.

The soundstage of both the Cayin RU6 and the Questyle M15 shows an efficient level of depth and wideness, while the M15 has the slightly edge when it comes to the depth and airiness of the stage. Another advantage of the M15 is its pitch black background that makes it easier to hear micro details.





Questyle M15 versus Shanling UA5:


The Shanling UA5 is the company’s new flagship USB DAC/Amplifier that I have reviewed recently. It is equipped with a build-in Lithium Battery that is part of its “Hybrid Power Mode” to reduce the power consumption of the source and to give the components a stabile energy source in order to increase the sound performance.

Both the Shanling UA5 is a premium looking device with a high build quality same like the Questyle M15. The UA5 is relative longer and thicker with dimension of 68x27x13.5mm (versus 61.8×27.2x12mm) while both are equal in terms of wideness. The UA5 comes with a small OLED screen that gives information about the gain mode, volume and sampling rate. Moreover it has a multifunctional wheel for volume adjustment and navigation that the M15 not has.

The UA5 is a pretty powerful device that offers both 4.4mm Balanced and 3.5mm Single Ended outputs like the M15. However the M15 is again more powerful compared to the UA5, especially at high gain, while both devices do offer a quite similar in terms of background noise performance, which is a tad cleaner on the M15. The Shanling UA5 is equipped with 2x ESS Sabre ES9038Q2M DAC chips, which do offer PCM decoding up to 32 Bit/768kHz & Native DSD up to DSD512, while the PCM and Native DSD decoding of the Questyle M15 is limited with PCM 32bit/384kHz and DSD256.

20220515_200956-scaled.jpg


The Shanling UA5 shows a slightly brighter tonality and more energetic overall sound signature, while the Questyle M15 shows tad more neutral tonality and more balanced presentation from the lows to the highs.

The lower frequency region of the M15 sounds more dynamic, fast and has also the upper hand when comes to authority in complex bass passages such like Gogo Penguin’s “Raven” or Charly Antolini’s “Duwadjuwandadu”. Both devices do offer a clean and detailed sub- & midbass presentation, while the M15 is the source with the more fluid and natural character in this area.

The midrange of the Shanling UA5 shows a slightly brighter tonality and a more energetic overall presentation, while Questyle has managed do create a more organic and liquid midrange character from an ESS DAC chip. Both the UA5 and the M15 do offer a pretty transparent and airy midrange atmosphere with decent level dynamics and resolutions that can compete with full sized Android DAP’s with double or even triple the price. The lower midrange of the Questyle M15 shows a bit more body that was audible when I have listen to acoustic guitars and violas, while both do offer a fairly similar performance in terms of resolution in this area.

The upper midrange of the Shanling UA5 is slightly more highlighted yet a bit dry and sharp when I do listen to female voices or to instruments like clarinets, violins or pianos. The Questyle M15 on the other hand sounds pretty controlled and natural in this area, which makes is more compatible with different earphones/headphones and enjoyable for longer listening periods.

The treble range of the Shanling UA5 is slightly more pronounced and energetic compared to those of the Questyle M15 that shows a more balanced and natural presentation in this area. The lower treble region of both devices is detailed, extends pretty well and offers a decent sense of clarity and definition. The upper treble register of the Shanling UA5 is a bit more highlighted and detailed, while the M15 offers a higher level of authority and separation.

The soundstage of the Shanling UA5 is slightly more expansive, while the Questyle M15 shows a better performance when it comes to the depth of the stage.

20220515_195425-01-01-scaled.jpeg




Conclusion:

I have tested many Ultra-Portable USB DAC/Amplifiers so that I can easily say that the Questyle M15 is one of the best available on the market. It immediately impressed me with its unique design, premium appearance and with its very natural, highly detailed and mature sound presentation. Moreover, it comes with both 4.4mm Balanced and 3.5mm Single Ended outputs that do offer plenty of power for demanding headphones and an ultra-clean background for sensitive In-Ear Monitors. All this features are packed in to a small device that can compete with full sized DAP’s that do cost twice or even triple the price that M15 has.


Thank you for the Read!​

Moonstar
Moonstar
Pirastro
Pirastro
Wow yet another reviewer working for Questyle. These reviews are starting to make me ill.
Moonstar
Moonstar
@Pirastro Sorry mate, I don't work for Questyle or any other Brand. You have just read my subjective opinions about a product that I have got for review. Cheers :beerchug:

OspreyAndy

500+ Head-Fier
Questyle M15 - Hi-Fi Sound on the Go
Pros: -
- Superbly well balanced neutral and natural sound
- Reference grade technical prowess
- Amazing driving power
- Highly versatile and adaptable to any partners
- Native iOS support
Cons: -
- I wish there was an independent volume adjuster
- Slightly larger in size compared to competitors

Questyle M15​

Review Date: 30 April 2022
0425221402_hdr.jpg

SPECIFICATIONS
Quad amplification engines
Flagship-grade ESS Sabre ES9281AC
Dual Headphone Output Ports(3.5mm Single-Ended+4.4mm balanced)
Two-level gain switch
LED indicators for gain and active bitrate
Low power consumption TOREX power chip
Technical Specs:-
Decoding Parameters: PCM 32-Bit/384kHz, DSD256
Output Interface: 3.5mm single-ended, 4.4mm balanced
Output Power(3.5mm): 11.97mW @ 300Ω, Vout (Max): 1.895Vrms
Output Power(4.4mm): 22.60mW @ 300Ω, Vout (Max): 2.624Vrms
Frequency Response: 20Hz-20kHz±0.1dB
THD+N: 0.0003%
Dimensions: 61.8×27.2x12mm

Test Equipment

IEMs and Earbuds:

  • Etymotic ER4SR (Single BA, 45 Ohm, 96db Sensitivity)
  • Shure KSE1500 (Single Electrostatic 200V, KSA1200 Energizer)
  • Kinera Idun Golden (3BA + 1DD Hybrid, 32 Ohm, 112db Sensitivity)
  • Tripowin HBB Olina (Single DD, 32 Ohm, 110db Sensitivity)
  • VE Asura 3.0 FE SLQ (Single DD, 155 Ohm)
  • VE Monk GONE SPC (Single DD, 32 Ohm)
  • BuduBuds V1 (Single DD, 32 Ohm)
Headphones:
  • FOSTEX T40RP MK3 (Magnetic Planar, 50 Ohm, 91db Sensitivity)
  • Beyerdynamic DT880 (Dynamic Drivers, 600 Ohm, 96db Sensitivity)
Sources:
  • Windows 10, Foobar 2000 (USB 3.0 Power)
  • LG V50 ThinQ (UAPP USB Exclusive Mode, Bitperfect)
  • Sony Xperia X Compact (UAPP USB Exclusive Mode, Bitperfect)
  • HiBy Music Player App (USB Exclusive Mode)


LISTENING EQUIPMENT USED IMPARTED HUGE INFLUENCE TO SOUND IMPRESSIONS & RATING

fw.png


At the time of my review, my M15 has been upgraded from FW Build 9086 to Build 9277 which can be downloaded directly from Questyle here:
https://questyle-en.oss-us-west-1.aliyuncs.com/Driver/M15 Firmware_v.0427.zip

Questyle M15 marked the progression and evolution introduced with M12, the only Current Mode amplification Dongles to exist now. It is no secret that among over 120 Dongles I owned, the M12 ranks the highest in my book for ESS Sabre unit. I even prefer it more over Apogee Groove and the slew of Hidizs S9 Pro, E1DA 9038 or REIYIN DA-Plus – all of which prime examples of properly tuned ESS Sabre units.

When M15 was released, gleefully I took the opportunity head first to have it delivered to my doorsteps. Full of anticipations and excitement. I know Questyle has great tuning principle and this is a known fact among many audio enthusiasts. Let’s see how does M15 fares in the real world shall we?

PS: As noted above, my M15 has undergone a Firmware update and the entirety of my review are based on it – post FW update.

Build, Functions, Usability​

0420221428a_hdr.jpg

M15 is a huge Dongle, in fact I daresay it is 3x the size of M12. It is probably the 3rd largest Dongle I ever owned. Apogee Groove being the largest then followed by CEntrance DACport HD. By current standards, M15 is one hell of a solid device construction wise. The traditional rectangular design being simple as it is functional.

Most prominent feature would be the glass faceplate on one side. The glass window would allow us to savor looking at the beautifully crafted internals. Clearly showing generous real estate of components. As I said earlier, M15 is large. The rationale behind this, Questyle opted to go purist route on M15. They forgo the need to downsize in favor of innovation, to ensure that M15 will have all the bells and whistles of a top of the line performer.
Feature wise, despite the size, M15 offers equally simple stuffs like imbedded led lights that can be seen through the glass window. One for power/resolution and another one for High/Low gain. On one side, there’s user selectable hardware switch for gain selection.

However, M15 does not offer any sort of volume adjusters on the Dongle itself. I must admit that I wished it would have include some sort of independent volume adjusters. What I have learned so far, independent volume adjustment does have big role in fine tuning listening loudness. As observed with the likes of Cayin RU6, DACport HD and Lotoo PAW S2 – all of which comes with super refined volume adjusters, the ability to fine tune volume levels has help to elevate music listening greatly – at least in the manner of how I normally use the Dongles – set the volume at Max on the host and let the DAC/Amp regulate the output. Perhaps Questyle can consider this in earnest in upcoming Dongle line-ups.

As for the volume adjustment itself on the host side, like most other Dongles without independent/dedicated adjusters, M15 depends largely on the volume steps resolution of the source. So in order to have fine adjustment, it is necessary to use HiBy Music App (Software Volume Mode) or UAPP Volume Steps. But at least I can tell natively M15 does offer “less jumpy” gain between levels as observed with some other devices.

While M12 came with just 3.5mm SE, M15 stepped up to the current standards of including a 4.4mm BAL Pentaconn port. Balanced circuitry that offers discrete power each channels (L/R) instead of shared GND. This has allowed them to push the power output higher and will work great with power hungry partners.

In alignment with what was already introduced with M12, M15 also offers the latest iteration of Questyle Current Mode amplification. I honestly don’t know much about this technology, so I would not dwell too much talking on it. But what I do know, the Current Mode amp stage of both M12 and M15 plays huge role in shaping up the sonic characteristics they offer.

As with most other Dongles nowadays, M15 comes with female USB C interface for the data link. This will allow for swapping of cables to suit the needs. Included in the stock package, M15 comes with both USB C and iOS Lightning cables. This effectively means that M15 is among the few that has been designed and built from scratch with versatile compatibility to iOS.

Despite being a “larger than normal” Dongle, M15 appeared to be adequately efficient with power draw to the host. With my Sony Xperia X Compact (Android 8, 2700 mAH Battery), M15 was able to clock 5-6 hours of continuous play – driving Tripowin Olina at low gain, USB Exclusive mode UAPP. This is pretty much on par to the competitions like Lotoo PAW S2 and Cayin RU6. Only xDuoo Link2 BAL and HiBy FC5 scored better at almost 7 hours.

Most impressive, M15 is probably the best Dongle DAC/Amp with heat management. Despite the larger size, M15 was able to stay relatively cool even on prolonged sessions.

Sound Impressions​

0424221023_hdr.jpg

Questyle M15 is a wonderfully balanced DAC/Amp. From the moment I plugged it in with my Etymotic ER4SR, I was already mesmerized with fluid, crisp, smooth and highly resolving output that does not exhibit any coloration in any frequencies. It is admirably organic and refined sounding. Despite being an ESS Sabre based DAC, there’s absolutely no hint of Pinna Glare or unnatural edgy brightness that is notoriously evident with most ESS devices. The signature of Questyle tuning, it is super clean with immaculate resolved notes and tones – while at the same time managed to avoid the pitfalls of sounding sterile and dry. If I am to turn back the clock over a year ago, when I first tried the older M12, I remember the output was already amazingly clean and pristine – however I did mentioned that M12 (with the old Firmware) has some tendency to emit some dryness. Questyle fixed that for good with M12 later version FW. What I am hearing now from M15, an evolution of that immaculate sound. Something that is exceedingly technical yet musical.

Perhaps if I am to nitpick, on a very personal level I normally prefer a bit more of analogue touch to the output, M15 seems to be not as analogue sounding when compared to CEntrance DACport HD, Ovidius B1 or Cayin RU6. M15 is more aligned with the Hi-Fi sound approach which is favored by L&P W2, HiBy FC5, Colorfly CDA M1 and REIYIN DA-Plus – which means among them all, I can easily say that M15 is the BEST of the crop with that Hi-Fi approach. That effortless dynamics and transients making it such a pleasure to listen to, the overall theme being crispy smooth, resolving and detailed.

On dynamic range, M15 is assuredly a stellar performer. The extensions on both ends nothing short of impressive. What I am hearing from my regular favorites of Shure KSE1500, Etymotic ER4SR and Fostex T40RP MK3 revealed how rich the extensions are. Highly detailed on macro and micro levels. Sub Bass being rich and dense, Treble being sparkly with proper texture, Mids being wholesome and engaging – and keeping it neutral, uncolored while at it. Never a moment I felt that any of the frequency range being emphasized beyond what is realistic.

Technically, M15 is an absolute beast. Just like the predecessor of M12, M15 carried on with that trajectory with some of the very best technical performances I have heard so far. Being critical, perhaps the only caveat that I can point out would be the average sized soundstage which I wished could be a bit wider. In this regard, I would say that the likes of xDuoo Link2 BAL, THX Onyx and DACport HD offers the widest soundstage still. M15 on the other hand is pretty much similar to Cayin RU6 and Lotoo PAW S2, it has breadth of space, depth respectfully spacious but just slightly short on absolute width.

What M15 does offer in spades, reference level of resolution, imaging, speed, details and separation. M15 is a device that will please even the most demanding need for technical indulgence for listening to highly complex music. The better the recording and mastering, the better it gets. For example, with highly complex Jazz composition, I was able to appreciate even the most subtle of nuances – presented with crisp imaging and cleanly defined layers. In fact M15 performed miracles with my favorite duo of Kinera Idun Golden and Tripowin Olina – elevating those two IEMs technically to TOTL level of performances, no joke!.

As I always mentioned, the hallmark of a great DAC/Amp – their ability to synergize with anything. And M15 is one such devices. Be it my super hard to drive Beyerdynamic DT880 600 Ohm and Fostex T40RP MK3, open back VE/BuduBuds earbuds, highly sensitive hybrid IEMs, even legitimate 200v Electrostatic of Shure KSE1500, M15 does it all with such guile and finesse. That’s how a true neutral DAC/Amp should behave – it does not show any specific preferences to what sound curves the paired partners have. It just works

Driving Power​

0430220810_hdr.jpg

Questyle M15 is a 2.62 Vrms rated dongle (4.4mm BAL). Despite not being a 4 Vrms device, M15 does have tons of power at its disposal. This is similar to the performances of Ovidius B1, Hidizs S9 Pro and Creative SXFi, the other 2 Vrms devices that offer tons of power to even handle super stubborn magnetic planars.

For my own usage, M15 performed spectacularly to drive Beyerdynamic DT880 600 Ohm with ease. On HiBy Music App USB Exclusive mode, M15 only needed 16/32 volume for proper listening loudness. On my PC it was at 40/100 max (any higher and it would be just too loud for my comfort). Simply put, the sort of performance offered by M15 in this scenario really cemented my belief that I don’t need a dedicated desktop DAC/Amp stack combo. Everything about the sound simply being wholesome and satisfying. No hint of micro jitters or distortion. It’s all about fluid harmonics end to end. I am not hearing any loss of micro details. About the only thing missing, perhaps absolute headroom sense, like 2% less headroom as compare to the output as heard from my iFi ZEN Stack of ZEN DAC V2 + ZEN Can. That 2% is totally negligible. The same can be said for the magnetic planar of Fostex T40RP MK3, one of the most stubborn planar headphones out there now – no sweat for M15.

On the other hand, despite all that power, M15 has also shown amazing synergy with super sensitive and easy to drive stuffs. I am getting super clean output from my Tripowin Olina and Kinera Idun Golden. Pitch black background even on the most silent of passages. This is consistent even on High Gain mode.

Volume Difference (With Etymotic ER4SR, HiBy Music App, USB Exclusive Mode)
SE 3.5mm = 12/32 (Low Gain)
BAL 4.4mm = 9/32 (Low Gain)

I am happy that both 3.5mm and 4.4mm ports shared identical sound quality. The difference only the absolute limit 4.4mm can go which is up to 600 Ohms. However for anything under 155 Ohm the 3.5mm will work as great as the 4.4mm side. Once volume loudness matched, I can’t hear any difference at all. This is simply amazing because I have heard many (if not all) Dongles being slightly inferior on the 3.5mm side, but M15 does not neglect this element. In comparison, the likes of Luxury & Precision W2 and Lotoo PAW S1 practically treated the 3.5mm port like a 2nd class subject.

VERDICT​

Questyle M15. All things considered, I am confident that M15 being one of the very few releases for 2022 that can claim 5 stars rating. Sound wise, M15 offered practically everything that I like about sonic performances. The balance of neutral organic timbre, totally uncolored and devoid of any unpleasant edginess commonly associated with ESS Sabre DACs.

M15 biggest strength being superbly versatile and effortlessly fluid in projecting Hi-Fi sound in a compact form factor. Yes it is 3x bigger than M12, but the size is well justified for a truly complete package when it comes to delivering sound quality. If I must be critical, then my only wish list would be an independent volume adjuster – had that been included, M15 would have assuredly been perfect.

Simply put, Questyle M15 has set a very high standard for how a great modern Dongle DAC/Amp should sound. It is amazingly well crafted to be competently technical as it is musical. Mesmerizing every time I listen to it.

0423221600_hdr.jpg

Best Pairing: Anything up to 600 Ohms​

#donglemadness
Last edited:
OspreyAndy
OspreyAndy
@LudwigVonMises If I have to choose only one from the three you mentioned, I am more partial to choose M15. Link2 BAL comes very close, so does MoonRiver 2. You must remember that all 3 are already excellent Dongle DAC/Amps and we are talking about small differences that separates them
C
Carroamaro
Excellent analysis...

How would you compare to Ve Megatron?
OspreyAndy
OspreyAndy
@Carroamaro The most evident difference between Megatron and M15 is that Megatron will exhibit audible floor noises for any pairing with sensitive IEMs. Sound wise they are pretty much similarly tuned to be neutral and organic. Megatron obviously have upper hand with outright power. Technically however I think M15 is more resolving, probably the most resolving dongle I have tried of over 122 units...
Top