Questyle M15 Portable Amp/DAC Review

The Questyle M15. The end to a long dongle journey?

I recently acquired a Questyle M15, one in a list of many dongles I have tried in search of “the One”.

My journey into portable audio gear started as a hobby to keep me from losing my mind during lockdown.

Since then I have been able to try only a small fraction of what is available in an ever increasing and improving market and generally gear orientated to my modest budget.

That being said I do like to get the best bang for my buck and to that end I tend to do a lot of research into an item before I purchase.

I have tried a number of dongles along the way looking for the one that would really grab my attention. From the cheap and cheerful JCALLY JM40 I bought for my daughter for school to the much lauded Audioquest Dragonfly Red that I managed to acquire on the cheap and ended up pairing with the original Tri i3s who planar driver really appreciated the extra power the Red provided, then giving to my son as I found it overly warm a sound signature amongst other faults. Also others like the Hiby FC3, a great cheap avenue to Tidals MQA or the Earmen Eagle of which I was lucky to get one of the first 500 models which has the chip from the Sparrow and renders MQA and is a very elegant and tidy dongle with good amplification and a very pleasing neutral sound signature and not forgetting my ifi Hip DAC a less portable option having its own battery but huge amplification coupled with the warm Burr Brown DAC chip signature. All good options and highly regarded, but all lacking in one way or another from what I would consider a great sound.

By great sound I do not mean to imply that I am a great audio critic. Far from it, too many years headbanging in front of towering speaker stacks have left these old ears lacking in refinement. But I have quite an eclectic taste in music. Music that is often very complex and intense and intricate and I want to be able to hear all those nuances in my everyday listening. When at home I have my desktop setup of Gustard X16/H16 coupled with Hifiman Sundara`s or my living room setup of Willsenton R8 KT88 push-pull valve amp into Triangle Borea BR03 speakers. For my vinyl I use a Project Debut Carbon USB.

Mostly I have gone for dongles that at least render MQA as I use Tidal as my streaming service. This was one of the factors that led me to the Questyle line of Amp/DAC`s.

Quite a few of the High End amp manufacturers have started to get in on the dongle craze of late. Cayin brought out the RU6, Luxury and Precision the W1 and 2 Astell and Kern the PEE51 and 52 and Questyle the M12 and now the M15.

Of these only the Questyle can render MQA so when I was looking to pick a contender from this new field of dongles in March, as a cheeky birthday gift to myself, it was the Questyle that caught my attention.

I purchased a Questyle M12 from Hifigo and it arrived in record time and my initial response was most favourable when used with my sons Tri i3s or my wifes BQEYZ Spring 2s but then I encountered a problem. When paired with my favourite IEMs the Mangird Teas, a 1DD/6BA setup that normally sounds exquisite, I encountered a clicking. Not just an occasional click but a constant tick, tick, tick. Further I found that it only happened with the MIUI phone software used by Xiaomi. I documented all of this and did a little video highlighting the problem and sent it off to Questyle. They got back to me very quickly and fixed the problem temporarily by rolling the M12 back to an older version of the firmware and they assured me that a new firmware was in the works and would be available soon. They also asked if I would be interested in reviewing their new M15 dongle Amp/DAC an upgraded, and more expensive, version of the M12 with the addition of a 4.4mm pentaconn balanced output and a gain switch.

I of course agreed. And a week later I received my M15.

The packaging is almost identical to that of the M12. The same sleek black box with a small cloth tab to allow ease of opening of the sliding tray. Inside the M15 is displayed in protective foam.

The first thing I noticed was that it is considerably larger than the M12, by about 250%. This was not really a problem though as the M12 is the smallest of dongles I have. In the end the M15 is not much larger than the Dragonfly Red.

The next thing I noticed was the glass front panel that allows a view of the inner workings of the M15. I have to admit that this really appealed to the geek in me, though my wife was less impressed.

Beyond that the box contains underneath a short Type C to Type C USB cable for connecting to your phone and a Type A to Type C for connecting to a PC or laptop. There was no included lightning cable but as an Android user this was not an issue.

And that is it. The packaging is simple, elegant and ecological.

The flip side of the M15 is similar to the M12 with the matte black finish and the Questyle logo in print.

On one end you have your USB C output and on the other both 3.5mm single ended output and 4.4mmPentaconn balanced output.

On one side you have a gain switch for low or high gain to better match the headphones or IEM`s you are using. A much welcome addition to the M15 that was not present on the M12.

Instead the M12 had a Smart Detect, Auto-Gain feature that was meant to match the impedance of your headphones with the amplification from the M12s Current Mode Amplification. This worked well with my selection of IEMs but when I tried out my Hifiman Sundaras with their planar magnetic driver and low impedance of around 37ohms I found that the M12 did not switch into High Gain Mode` and therefore did not put out enough power to drive them to very loud volumes.

Not so the M15.

The first thing I did was to try it out with my Xiaomi phone and my Mangird Tea IEMs and I was pleased to find none of the clicking problems I had experienced with the M12s firmware. Volume wise I was only able to take my phones volume to the 50% mark.

The second thing I did was to try it with my Sundaras. At first I thought the M15 was not up to the task, but only until I realised that I had not switched it to High Gain` at which point it provided more than sufficient power. I really must start remembering to turn my phone volume down when I change devices.

The M15`s Current Mode Amplification pumps out copious amounts of power. Even for more power hungry drivers like planars. What is more it does not get muddy and lose coherence at higher volumes like I have found with many dongles. Imaging was excellent even with the power turned up to almost ear bleeding levels.

Satisfied that I had plenty of power to play with I sat down for a more critical listen.

I lost hours!

I had initially only planned to spend a couple of hours but the next thing I knew it was 5am and work was but a few hours away. This Amp/DAC dongle is amazing! I was sat in bed streaming via my mobile and it sounded as good as most desktop systems I have tried and indeed better than a great deal of living room setups. I was in audio heaven.

The basic sound signature is neutral to the point of being totally transparent. You get exactly what was recorded as it was recorded. Nothing is too forward or over expressed.

The soundstage is wide though not overly but it also has depth which gives it a three dimensional presentation. You can really hear and feel the spaces between the instruments.

And all of this on the 3.5mm SE output!

Next day I swapped out to 4.4mm balanced Pentacon cables on my Sundaras and my Mangird Teas and to be honest the only difference I noticed with the Tea`s was that I could now seriously damage my hearing if I was not careful with the volume. This was quite a surprise as, from my reading, most dongles with both tend to pay less attention to the 3.5mm output but this is clearly not the case with the M15.

With the Sundaras there was a noticeable increase in volume and power which opened up the planars in a way I have only ever experienced before with desktop setups. This thing actually comes close to my Gustard X16/H16 setup in both reference level clarity and precision and whilst it does not have quite as wide a soundstage it has more than enough amplification to drive the planar`s to their true potential.

Musically the M15 is exactly what I was looking for. I like an Amp/DAC to be neutral and not to colour the original recording. I want to hear the recording exactly as the artist recorded it. And in this the M15 excels. Nothing is too forward or recessed. Bass comes in with just the right amount of thump, trebles are not too shrill or fatiguing and as for the mids both male and female vocals are right on par.

Whilst this may seem a little dull for some, doing this well is a considerable challenge if some of the competition are what you go by.

The M15 provides a level of detail in the music that is rarely heard in a dongle. From the simple acoustics of the Blister in the Sun by the Violent Femmes to the complex musical morass of Pictures of a City by King Crimson the M15 delivers like no other portable device I have tried. You can hear the guitarists fingers slide along the frets.

Bird and Diz sang like never before Buddy Ritchs most excellent percussion and Curly Russells Bass on Bloomdido always gives me that warm fuzzy tingle. Sat back in my chair I almost felt like it was coming from my main system. I got the same euphoric waves of emotion running through me that I have come to expect from high quality audio listening.

It did not matter what I threw at the M15 it handled it well. From Reggae, Dance, Rock, Punk, Psychedelia, Avant Garde and Jazz it handled all with ease delivering a superb playback. I even loaned it to an audiophile friend who listens almost exclusively to classical as I have very little experience in that genre and he was delighted with the M15.

I have taken the M15 through a sizable chunk of my catalogue over the last few weeks and have been able to find very little to fault it. After such a magical musical journey griping about volume controls or a tempered glass screensaver or a case as standard seems petty, though I think the M15 would benefit from volume controls I always have difficulty finding just the right volume level with my phone. I have found that using the hardware volume control on the Hiby music app is far more precise than my phones volume slider.

So is the Questyle M15 “the One”?

I can only speak from personal experience but I feel the M15 has checked all the boxes. It provides amplification sufficient to drive a set of planar over ears to their true potential whilst at the same time being delicate enough for the most sensitive IEM`s. It delivers a transparent, reference level playback with great soundstage, imaging, clarity and resolution in both 3.5mm SE and 4.4mm balanced outputs. It is not overly power hungry on your phone. It is elegant and whilst being larger than most dongles it still classes as such in that it is readily portable.

Simply put the M15 is the best dongle Amp/DAC I have ever come across and whilst I am always interested in testing new tech I feel that I shall no longer be actively seeking a replacement. The M15 has defiantly become my go to option for a portable Amp/DAC.

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Since posting Questyle have sent me a sample of the new M12 firmware and after testing, it seems they have eradicated the clicking problem with MIUI completely. I have listened to a few dozen tracks from a plethora of genres and have not noticed a single click.

Yep, I agree :100:%

It’s also my Nr.1 Dongle-Choice

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Whatever Questyle is doing with this tech I’m all in, very curious on their desktop dac/amps now. Running with Raptgo Hook, Letshuor S12, and 7HZ Timeless, Planar bass is just massive…

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Hey guys does anyone know of a converter to output the Bluesound Node 2i to the M15? Like a Toslink or Coax to USB-C converter? Appreciate the help.

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

As always, this is a non affiliate link.

Intro…

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

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

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

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

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

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

Presentation…

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

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

Build and aesthetics…

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

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

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

Functionality…

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

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

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

That is it. Not much to explain.

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

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

Sound…

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

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

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

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

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

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

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

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

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

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

Conclusion…

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

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

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

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


As always, this review is also available in Spanish both on my blog (www.achoreviews.com) and on YouTube (www.youtube.com/achoreviews)

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I agree :100:

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I’ve been on a hunt for discounts on the M15 and its siblings since I decided their linear-all-the-way CMA implementation is state of the art, something all dongles should’ve been doing forever, and that its response is perfectly neutral, based on an assortment of reviews mostly calling it neutral and a minority calling it too bright.

But since I haven’t yet seen a price I really liked, yesterday I decided to take just one more look at Professor Wolf’s measurement results, especially the frequency response, and now I’m in a dilemma again.
https://cdn.l7audiolab.com/wp-content/uploads/2022/07/Relative-Level-1.jpg

Ever so slightly veiled, but still veiled. I don’t have the luxury of caring about that wild almost 1 dB drop at 20 kHz but I can still hear up to 15k, and a tilt going to -0.256 dB at 16k could be audible. After all, the research says we can hear tilts of even 0.1 dB across a whole octave, so even if this -0.2 was stretched from 10k to 20k some listeners would still hear it. The narrower tilt this has is even easier to detect, and we can tell from the many reviews that - like yours - describe the M15’s sound as “neutral but not harsh / clinical / sterile / cold / fatiguing”.

I like the Hiby FC3 and I’ve liked its tonality vs. everything I’ve compared it to, and I’m talking big names, each praised to high heaven after release, like iFi Micro, Oppo HA-2 and FiiO KA17. There was a possibility it was boosting treble somehow and that was why everything else sounded warmer than it, but I measured it just recently and it came out perfectly neutral all the way to 20k. So I’m taking the view that most everyone is doing neutrality wrong, and it seems the endgame source I’m looking for should have that “harshness” and “fatigue” (lol) and “clinical” sound, because that is neutrality and it sounds damn good to me.

So thanks for the pointer to look in the direction of the S9 Pro :grin: (I think there was one other reviewer who said the S9 Pro Plus Martha was super neutral, but I couldn’t rely on that since so so many others say it’s “neutral warm” or “natural warm” - maybe I should be looking for a different Pro). But it’s still a painful question whether to give up the current-mode amplification for perfect neutrality or just accept I may have to create double the number of EQ profiles, not just for each headphone but for DAC-headphone combinations, so as to counteract the M15’s built-in veil.

LE:
Nope, S9 Pro (non-Plus, non-Martha) is also not ruler-flat. It’s better at 20k but because it rolls off smoothly it’s about the same at 15k: https://www.audiosciencereview.com/forum/index.php?attachments/fr-png.207229/