You get what you pay for; not with the Questyle M15, you get much more! If you don’t want to read further, let me make it short, you get top class desktop grade audio performance in DAC that fits on the palm of your hand.


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




Physical Attributes & what's in the box:


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


Specifications:


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

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


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




Pairings:


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

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

The M15 did not fall short with any of them.


Sound Impressions:


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


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




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




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


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


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


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


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




Conclusion:


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