Questyle M15i Portable DAC/Amp Review

The M15i is the successor to the original M15 that Questyle released a couple years ago. This new update features built-in Apple support and bug fixes from the original M15. For the most part, this looks identical to the original except the branding and some LED lighting style.

This product retails for $299, but is often on sale for $249. I purchased this directly from Questyle via their store.

The M15i is a dual-output dongle with 4.4mm balanced and 3.5mm unbalanced jacks. Both of these appear on the rectangular device with a really neat fully transparent top. This allows users to peer into the Printed Circuit Board and its components that does all the work. On the board are a pair of LED sections that notify the user of the gain level and the sample rate of what is currently playing. There was a small update here from the previous generation, with the gain selection showing up as 1 or 2 small red indicators, instead of a single red or green LED illumination.

The device uses USB-C for output and it is worth noting that it only takes USB-C OTG cables. A standard USB-C to USB-C cable does not work on this device like it does on some other dongles I have used. I did have no problems using USB-C to USB-A cables though. 

The device can output up to 2.624 Vrms (or about 22mW at 300 ohm) on its 4.4mm connection, and 1.8 Vrms on its 3.5mm connection. The M15i, like other Questyle products, uses a proprietary current-driven amp design, which in this case, allows it to work more optimally to lower impedance headphones that work better with higher current as opposed to higher voltage. This, as they claim, also optimizes battery usage better.

On the M15 and M15i models, there is a physical gain switch to change from Low and High settings. The lower end M12 and M12i models do not have this physical manual adjustment, and auto-selects the gain based on what it thinks is needed, for better or for worse.

Sound Impressions

I had listened to the Questyle M12 previously and wasn't a big fan of its sound presentation. It was lean, bright, and a bit too sterile for my tastes, and didn't enjoy it unfortunately, despite being a wonderful sized dongle. I also never got to listen to the original M15, but luckily the M15i is a step-up from the M12 sound signature.

The M15i is still fairly neutral, but has a slight V-shape to it, with accentuated lows and upper treble air. It's just a subtle dose of warmness and air that gives this a fairly tasteful, neutral sound signature that isn't sterile or overly analytical. 

The bass range is quite punchy and dynamic. On hip hop tracks, the drum beats are both impactful and can pulsate you on the Symphonium Titan. The M15i also has great bass texture capability. I think the overall resolution is really outstanding when compared to other portable DAC/Amps I have tried. 

This could possibly be due to the slightly bright treble tuning that makes it details stand out, but its not overly done to become fatiguing or bright/sharp. Instead, the M15i is quite listenable, and really shows off the technical abilities of the Subtonic Storm and its high dynamic range, and ultra-resolving nature.

When I compare it to some other dongles I've tried, it quickly stands out as the most resolving. I listened to it side-by-side for a while with the M12 and also the iFi Go Bar and the Violectric Chronos. The M15i was the most dynamic and transparent of the bunch, but didn't lose anything in terms of warmness and body. 

The Chronos is probably the most full of the bunch, but had the smallest soundstage and the iFi Go Bar was a good in-betweener of the three dongles here.

It's been quite sometime since I've owned the Cayin RU6 and an extensive listening session with the RU7, but both of these are easily much more analog and warm and rich in nature, and the M15i is a completely different sound signature, with its more extended treble air and more incisive sound.

The M15i sound signature probably mostly resembles a very small version of the Chord Qutest to me, from memory again. It is a DAC that I owned for a couple years and really enjoyed for its incisive attack, sweet treble, and great resolution. The M15i is less sweet up-top but still presents an enjoyable sound.

Final Thoughts

I really do dig this blind-buy purchase. It's a contrast to a lot of the stuff I've recently owned and enjoy, as it's on a brighter and more neutral tilt than my Fiio M15S audio player, and my Holo Spring KTE R-2R DAC and Bliss combination.

I love the small size of it, and the cool-looking design. It's still quite a bit pricier than other dongles, but at the same time, this is one of the most resolving ones I've heard to date.

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