Questyle M15 Review
Divine current on the go
Pros: + Musical and organic sounding
+ Realistic timbre and minimum digital glare
+ Excellent technicalities
+ Crystal clear and transparent
+ Dynamic and impactful
+ Dead silent and free of EMI noise
+ Can drive efficient headphones
+ Low power consumption
+ Stays cool even after hours of use
+ Unique appearance
+ Excellent build quality
Cons: – Lack of on-board volume control and hardware buttons
– Not as powerful as the competition
– Carrying case and lightning cable are extra
– Bright LEDs
The review sample was kindly provided free of charge in exchange for an honest review.
I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links.
The price of the M15 is $249 and you can order it directly from Questyle shop or all authorized dealers around the world.
Questyle Audio is dedicated to the research of high-tech lossless audio systems with perfect sound aesthetics and convenient listening experience, and provide the corresponding products, system solutions or key components according to customer requirements.
They are famous for their Current Mode Amplification topology that uses current, instead of voltage, to amplify audio signals.
Their CMA Fifteen is one of the most awarded and well regarded all-in-one systems thanks for its unparalleled performance as you can find out by reading the related review.
After finishing the CMA Fifteen review I was very curious to find out how the Current Mode Amplification performs in a portable device so I contacted Questyle who were very responsive and kind enough to arrange a sample.
The Questyle M15 is a USB DAC/amp dongle containing two of Questyle’s patented CMA (Current Mode Amplification) SiP modules, for a total of four CMA amp engines.
This quadruple drive amplification circuitry gives an outstandingly strong output that can drive almost any headphone.
Questyle’s Current Mode Amplifiers are characterized by their small footprint, low voltage operation, and minimal power consumption.
Current Mode amplification has a naturally low impedance, affording the M15 a bandwidth up to 1MHz and distortion as low as 0.0003%.
The M15 supports both unbalanced (3.5mm) and balanced (4.4mm) outputs with a manual gain adjustment via the slider on the side, which makes it easy to choose high/low gain depending on the connected headphone.
The M15 features the highly acclaimed ESS ES9281AC flagship DAC chip to do the decoding and can handle up to PCM384kHz/32bit, DSD256 and full MQA unfold.
The M15 also uses a TOREX, high-efficiency, power management unit for low power consumption from the host device without getting overheated.
Appearance and build quality
The M15 has a minimalistic design with a black metal housing that is made from CNC machined aluminum and a transparent glass cover which allows for the internal PCB to be fully visible.
A very innovative design that differentiates the M15 from the competition giving it a uniquely looking appearance.
Build quality and finish are excellent, there are no rough edges or sharp corners but I have some reservations about the durability of the glass.
The 61.8×27.2x12mm measuring M15 is compact and lightweight, at least for a dongle with two headphone outputs.
This is a simple to operate device, no drivers are needed, the only thing you have to do is to plug it to the host device with the supplied detachable cable to the USB type-C port and then your headphones to either the single ended or balanced outputs.
The device will power itself only when a headphone is plugged in so you can leave it hanging from your phone without consuming power if you have your headphones unplugged.
The M15 is lacking an on-board volume control so you are restricted to your phone’s steps for volume adjustment which is not that ideal.
Inside the unit and close to the USB port there are located two indicator LEDs that are quite bright.
One is for displaying the sample rate (Green ≤ 48kHz, Red>48kHz or DSD and Magenta for MQA) and the other for the gain (Red=high, Green=Low).
Inside the box you are going to find two short USB cables of high quality.
USB-C to USB-C and USB-A to USB-C.
A lighting cable and a premium leather case are available as extra purchases.
The M15 was left playing music for about 100 hours in order to settle down.
During the evaluation period I used various headphones and earphones like the Focal Clear Mg, Sennheiser HD660S, Meze 109 PRO, FiiO FDX and Unique Melody Mext.
All headphone cables are from pure silver made by Lavricables.
With a maximum output voltage of 1.895Vrms from the 3.5mm jack and 2.624Vrms from the 4.4mm, the M15 is not the most powerful dongle when considering that most of the competition can usually do 4Vrms from the balanced output while the iFi Go bar can go as high as 7.5Vrms.
But sometimes lab measurements can be deceiving and the truth is that the M15 provided plenty of juice for driving efficient headphones like the Focal Clear Mg and the Meze 109 PRO.
Background noise is pretty inaudible and the M15 is well shielded so it doesn’t pick electromagnetic interference.
The M15 stays completely cool even after hours of continuous use and it has a relatively low power consumption.
Plain and simple, the M15 is the most naturally sounding ESS dongle that I have reviewed so far with the less (if not completely absent) digital glare while retaining all of the famous ESS transparency and excellent technicalities.
It seems that the “current mode amplification” modules are making a great job into producing a very musical sound signature with an analogue-like and organic timbre.
Listening with the M15 is an enjoyable and engaging experience that is characterized by the surplus of musicality.
The tonality is realistic with plenty of colorful overtones that help instruments and voices to sound harmoniously intense and complete.
At the same time the M15 is a competent technical performer with supreme fidelity, absence of coloration and frequency response irregularities, petty thundering dynamics, excellent resolution and crystalline clarity.
There is no kind of music that is not suitable for the M15 while headphone matching is really not an issue because the M15 makes sure that you are listening to your headphones and not the device itself.
The bass is deeply imposing, fast, precise and controlled with excellent layering and definition.
The texture is not too visceral but not lean either, balanced would be the word to use while dynamics sound contrasted and impactful.
Mid-range consistency is great; the sound is coherent and articulated with a lush and rounded texture without becoming warm or romantic.
This is the part of the frequency range that has the richest harmonies and the purest timbre helping instruments and voices to sound very alive and close to reality.
The treble extension is amazing, the M15 is lively and sparkling sounding with excellent detail retrieval and plenty of airiness but without any of the brightness and forwardness that are usually associated with most ESS DAC implementations.
Smooth enough, without sharpness or edginess and very controlled when it comes to digital glare, the M15 is the kind of DAC that is heartily recommended for all day listening without causing treble fatigue.
The soundstage, given that you have the right headphone, can become very speaker-like at least as far as a dongle can go.
It is grand sized with sharp imaging and tactile arrangement of the performers with plenty of spatial information and natural reverb.
The listener feels like sited in the second row of the concert hall making the M15 ideal for listening to large scale symphonic and choral works.
Compared to the iFi Go bar ($329)
I consider the iFi Go Bar (and the Cayin RU-6 ) the references when it comes to musicality and organic timbre so a comparison, with at least one of them, was pretty inevitable.
Comparing the Go bar with the M15 proved that are on the same league of musical presentation with some minor differences.
The M15 has the lead in technicalities because it offers better clarity, it sounds more defined and resolving, it has faster transients, more contrasted dynamics and impactful bass.
But it sounds relatively drier when compared the more organic, tube-like and fuller sounding Go bar.
Additionally the Go bar feels more relaxed and loose around the notes, not as fast and not that firm or controlled.
The Go bar has a more holographic soundstage presentation but the positioning of the listener is closer, more intimate, almost next to the performers.
On the non-audio related stuff, it is the minimalistic M15 against the full featured Go bar which offers four digital reconstruction filters, XBass+ and XSpace analogue processing modes and iEMatch.
The Go bar has also an on-board volume control and physical buttons and it is more powerful than the M15 but with the disadvantage that it is not that power efficient.
The Go bar is about $80 more expensive than the M15 but the package includes a lighting to USB-C cable and a carrying case.
In the end
The Questyle M15 is not only the most uniquely looking USB DAC dongle among the competition but is also the most uniquely sounding because it manages to combine top level technicalities with the most musical and organic sounding character almost surpassing every other USB DAC dongle.
Very efficient and simple to use, the only thing you have to do is to plug your headphones and let be carried away by the divine current into the most musical adventure.
Copyright – Petros Laskis 2022.