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Review: Questyle M15 – Liquid Gold

Listen in style with Questyle!
Listen in style with Questyle!

The Questyle M15 is a sound investment for dongle aficionados. It is an almost complete package, boasting an uncolored neutral signature, excellent functionality, good power on tap, and class-leading technicalities.

Thank you to Questyle for providing the Questyle M15 review unit.

Ranging from from sub USD$10 to a few hundred bucks, dongle DAC/amps are dime-a-dozen nowadays, and are a favorite portable source for audiophiles who do not want to lug a DAP on-the-go.

As well as pairing them with phones and DAPs, dongles can be plugged into laptops and desktops too, so they are a pretty versatile source for music, gaming, and online meetings.

Listen in style with Questyle!
Bottom Line

Liquid gold describes the M15 aptly, with musicality meeting technicality. From high sensitivity/low impedance fussy IEMs, all the way to low sensitivity/high impedance beasts, the M15 can handle everything with ease. The build is solid, there’s more than sufficient power on tap, and it does not get noticeably warm with usage. The M15 is compatible with various file formats and devices, making it very versatile. Some small nitpicks are that there is no independent volume control, the dongle is rather large, and possibly some rivals may pump out slightly more power.

What We Like
  • Excellent build, with detachable cable.
  • Does not get hot even with long usage.
  • Class-leading technicalities.
  • Fatigue-free signature, balancing musicality with technicalities.
  • Authentic timbral accuracy, uncolored neutral sound.
  • 4.4 mm (balanced) and 3.5 mm (single-ended) outputs available. Low and high gain options.
  • Big power on tap to juice up demanding gear.
  • Dark background without hiss, compatible with low impedance fussy gear.
  • Compatible with multiple devices and music file formats.
What We Don't Like
  • No independent volume controls.
  • Some rival dongles may have marginally more power.
  • On the larger side for a dongle.

There is no doubt that portability is their forte, but can dongles rival desktop setups and DAPs for sonic fidelity? Are there compromises to be made when using a dongle? Does size really matter?

Today we will check out Questyle’s flagship dongle, the M15. Hopefully, this nifty dongle synergizes portability with excellent sonics!

Company Overview

Questyle was founded in 2012 and is based in Shenzhen, China. Questyle focuses on mobile and wireless audio solutions and has been awarded various international industry prizes, such as the CES Innovation Award, iF Industrial Design Award, and VGP Lifestyle Award (just to name a few).

Some excellent products in their stable include the Questyle M12 dongle, desktop sources such as the CMA 15, CMA400i and CMA 12, and DAPs such as the QP2R and QPM.

Technical Specifications

  • Form: Portable DAC/amp (dongle)
  • Removable Cable: Y (USB-C)
  • DAC chip: ES9281AC (ESS flagship chip)
  • Decoding format: PCM: 32kHz – 384kHz (16/24/32Bit), DSD64 (1Bit 2.8MHz) , DSD128 (1Bit 5.6MHz), DSD256 (1Bit 11.2MHz)
  • Source Jack: 3.5mm single-ended and 4.4mm balanced
  • Output impedance: 3.5mm: 0.96 ohm, 4.4mm: 1.22 ohm
  • THD+N%: 0.0003%
  • Frequency Response (Hz): 20 Hz – 20 kHz
  • Output: 3.5mm: RL = 300Ω, Po =1 1.97mW, Vout(Max) = 1.895Vrms,THD+N=0.00045% 4.4mm: RL = 300Ω, Po = 22.60mW, Vout(Max) = 2.624Vrms, THD+N=0.00057%

Packaging

I promise you that what's inside is amazing in terms of sound!
I promise you that what’s inside is amazing in terms of sound!

In the box

  • Questyle M15 dongle DAC/amp
  • USB Type-A to USB Type-C cable
  • Type-C to Type-C cable
A detachable cable is always welcome, as non-detachable gear may be a potential point of failure down the line.
A detachable cable is always welcome, as non-detachable gear may be a potential point of failure down the line.
Apple users need to source an aftermarket Lightning to USB-C cable or adapter.

Questyle is offering a complimentary leather case with the M15 for purchases made on or before May 31, 2022.

Design/Compatibility

The M15 is rectangular and is fashioned from CNC (computer numeric control) machined aluminum. Build is very solid. The M15 measures 61.8 mm X 27.2 mm X 12 mm, which is admittedly quite large for a dongle.

On one side, there is a transparent glass screen to see the innards of the dongle (this is a boon for the techies here!), and the other sides are covered in jet-black metal. The base of the dongle features Questyle’s logo.

On one end of the dongle, there is a USB-C female connector, and on the opposite end, lies the 3.5 mm/4.4 mm output, making this device compatible with single-ended and balanced gear.

The M15 is meant for plug-and-play usage, and is advertised to be compatible with:

  • Android: Android 5.0 and above
  • PC: Win10 1803 and above
  • Apple phones: iOS (as mentioned, one will need to get an aftermarket OTG cable for Lightning to Type-C)
  • Apple computer: Mac OS

I am not an Apple user, but had no issues pairing Windows 10 desktops and laptops with the M15, with no driver installation required. For those using legacy or older hardware, you may want to email Questyle to check whether you might run into compatibility issues.

As of the time of writing, Questyle has released a firmware update (FW 9086 to 9277) to increase compatibility with older Apple and Android phones, found here. Indeed, when I first tried this dongle with an ancient Vivo Y15 phone, it could not recognize the M15; thankfully, post update, everything went off without a hitch.

The rest of the review is conducted with the new 9277 firmware installed.

Questyle advertises that the M15 is compatible with multiple music streaming platforms, including Apple Music, Tidal, and QQ Music. In addition, the M15 fully supports and decodes ALAC, FLAC, MQA, and other lossless formats, making this an extremely versatile beast. Indeed, the M15 can handle demanding audio rates of up to PCM384kHz/32bit and DSD256.

Gain switches are found on the side of the dongle, and can be manually adjusted, unlike its predecessor, the Questyle M12. The low gain setting is more apt for high sensitivity and/or low impedance gear, whereas the high gain option can be tried for more demanding transducers, such as low sensitivity/high impedance sets, or outliers like planars.

Unfortunately, there are no independent volume controls on the M15, but this is just a small nitpick in the big scheme of things, as one can fine-tune the volume on the upstream source it is connected to. However, it behooves the user to check the volume level on the connected source before starting the music!

Internals

The M15 utilizes an ESS ES9281AC DAC chip, which is their erstwhile flagship DAC. Within the M15 are four patented Current Mode Amplification engines.

Churning out 2.624 Vrms on the 4.4 mm balanced output, the M15 has quite a lot of juice on tap.

During usage, 2 LED lights will turn on, one signals the active bitrate while the other indicates the gain level. As detailed in this photo, on the left hand side, there is a “DATA” LED on the top and a “GAIN” LED at the bottom.
During usage, 2 LED lights will turn on, one signals the active bitrate while the other indicates the gain level. As detailed in this photo, on the left hand side, there is a “DATA” LED on the top and a “GAIN” LED at the bottom.
LEDDescription
GAIN LED, greenLow gain
GAIN LED, redHigh gain
DATA LED, greenLow sample rate (44.1/48 kHz PCM or less)
DATA LED, redHigh sample rate (88.2 - 384 kHz PCM or DSD 64/256)
DATA LED, magentaMQA

A really cool point to note, is that the M15 gets only minimally warm when used on high gain/balanced mode with demanding gear, which is nothing to sniff at considering the amount of power on tap. In contrast, the Colorfly CDA M1, a rival with a similar 4.4 mm/high gain setting, gets way hotter with extended usage.

The M15 boasts some superb objective measurements. It has an ultra-low distortion of THD + N of 0.0003% and an impressively low noise floor.

Background noise of the M15 is < -125dB FFT @1kHz@48kHz(SR)24bit, @3.5mm Po=5.9mW, RL=300Ω. Data from Audio Precision AP2722. (From: https://questyleshop.com/collections/mobile-dac-map/products/m15)
Background noise of the M15 is < -125dB – SINGLE ENDED
FFT @[email protected](SR)24bit, @3.5mm Po=5.9mW, RL=300Ω. Data from Audio Precision AP2722. (From: https://questyleshop.com/collections/mobile-dac-map/products/m15)
Background noise of M15 is < -130dB FFT @1kHz@48kHz(SR)24bit, @4.4mm Po=23.21mW, RL=300Ω. Data from Audio Precision AP2722. (From: https://questyleshop.com/collections/mobile-dac-map/products/m15)
Background noise of M15 is < -130dB – BALANCED
FFT @[email protected](SR)24bit, @4.4mm Po=23.21mW, RL=300Ω. Data from Audio Precision AP2722. (From: https://questyleshop.com/collections/mobile-dac-map/products/m15)

Questyle M15 Sound

Tests were done with a myriad of transducers, from low impedance gear such as the Audiosense T800 and TRI Starsea, to low sensitivity IEMs such as the Final Audio E5000, up to harder to drive 300 ohm loads, such as the Sennheiser HD650 and RY4S 300 ohm.

The M15 managed to power everything without breaking a sweat.

The M15 effortlessly powers high sensitivity IEMs all the way to the notoriously demanding Final E5000; 300-ohm gear also pass the test with flying colors. The infamous Final E5000 can sound bloated and nebulous in the bass when not powered well, but the M15 tackles this beast with aplomb!

Some dongles may have their single-ended outputs throttled or implemented less well than the balanced outputs, but this is not the case with the M15. The two outputs sound similar, with the high gain setting only giving more headroom.
Some dongles may have their single-ended outputs throttled or implemented less well than the balanced outputs, but this is not the case with the M15. The two outputs sound similar, with the high gain setting only giving more headroom.

I’m glad to report that the M15 has no hiss with highly sensitive transducers and has a very silent and dark background. When paired with fussy low impedance gear (based on the rules of eights), the M15 does not skew the frequency response, due to its low output impedance (3.5mm: 0.96 ohm, 4.4mm: 1.22 ohm).

The M15 has an essentially dead neutral and very balanced sound signature.

Putting the M15 through its paces with some of my daily drivers, such as the Sony IER-M9, Sony XBA-N3, Tanchjim Oxygen, BQEYZ Autumn, Final E5000, Audiosense T800, Moondrop KATO, and the LZ A7, these transducers sounded uncolored, with their house signatures (and quirks) faithfully reproduced.

Some dongles may suffer from sub-bass and higher treble roll-off, but the M15 faces nothing of the sort, with excellent extension at both ends. On frequency tests, bass reaches down to 20 kHz (assuming one has a transducer that can reach this low), and bassheads worth their salt will enjoy the visceral rumble this dongle can generate.

Bass is fast, controlled, and clean, with excellent texturing and speed. The midrange is lush and natural, yet detailed, while the timbre is organic and authentic. Mid-lovers will have a field day with the cliche of new details being heard in the music with the M15.

This dongle has a very well-implemented ESS DAC chip, with no dreaded “sabre glare” in play. Treble is crisp, well extended with good air, yet smooth and fatigue-free.

The soundstage is spacious in all three dimensions, and layers of music can be heard, especially when paired with a technically-proficient transducer. Imaging, transients, dynamics, micro-details, clarity, and instrument separation are top-notch and are highlights on this dongle.

In fact, the M15 beats my previous favorite dongle, the Colorfly CDA M1 in the technicalities department, which we will talk about below.

In a nutshell, liquid gold describes the M15. It is extremely musical, yet sports class-leading technicalities. Think of smoothness meeting an analytical signature, melded into a nice little package.

Comparisons

The Colorfly CDA M1 is another neutral dongle that has gain settings and 3.5 mm/4.4 mm output options.

The CDA M1 can likewise power high sensitivity/low impedance gear all the way to demanding planars, but is less technically adept, losing to the M15 in imaging, micro-details, and instrument separation. The CDA M1 also has some sub-bass roll-off, which is not present in the M15.

Of note, the CDA M1 gets much hotter than the M15, albeit it has slightly more power and headroom than the Questyle M15, with a 4 Vrms output on the 4.4 mm balanced connector.

The CDA M1 is cheaper and smaller in profile, but if one has the extra coin, I recommend the M15 due to the improved technical performance and less heat generated.

Where to Buy

Despite containing an ESS DAC chip, the M15 eschews the ESS sabre glare that plagues other dongles containing ESS chips.
Despite containing an ESS DAC chip, the M15 eschews the ESS sabre glare that plagues other dongles containing ESS chips.

Conclusion

Liquid gold describes the M15 aptly, with musicality meeting technicality. It is a sound investment (pun intended) for those looking for a portable and well-rounded source.

From high sensitivity/low impedance fussy IEMs, all the way to low sensitivity/high impedance beasts, the M15 can handle everything with ease. The build is solid, there’s more than sufficient power on tap, and it does not get noticeably warm with usage. The M15 is compatible with various file formats and devices, making it very versatile.

I also appreciate that there are gain settings and single-ended/balanced connectors on offer and it is hiss free with a dark background. Technicalities are a major highlight, coupled with a very neutral tuning that does not add unnecessary coloration. What more can one want in a dongle?

Indeed, the best compliment I can give this proficient dongle, is that in the 3 weeks I had the privilege of testing out the M15, I didn’t miss my desktop setup (Khadas Tone Board DAC -> Schiit Asgard 3 amplifier) much, and actually used this dongle more often!

The M15 offers an ALMOST complete package for a dongle DAC/Amp.

Well, nothing is perfect, although the M15 is very close to achieving it. Some small nitpicks are that there is no independent volume control, the dongle is rather large, and possibly some rivals may pump out slightly more power. But those are areas I can overlook, considering the other overwhelming benefits that the M15 brings to the table!

In essence, liquid gold awaits the listener. This dongle is highly recommended, and getting one may possibly future-proof your source chain for some time to come!

2 comments

  1. hi, thx for the review 😎 is it worth to get the M15 if i have the Mojo2? does the M15 have a lush midrange, is it a good pairing with an Etymotic IEM?

    1. Hi Sir/Mdm

      Yes the M15 midrange is quite lush, it is not overly boosted, as the bass, treble and midrange are all well-balanced. I don’t have any etymotic series IEMs with me on hand currently, but based on specs, the M15 should make a good pairing with them.

      But since you have the Mojo2, the Mojo2 has more power for sure. The Mojo2 is not a dongle though, and needs charging with a battery life of 8 hours, whereas the Questyle M15 is a plug-and-play dongle, so I guess the usage is a bit different.

      I auditioned the Mojo2 a few weeks ago and it is quite a nice source for sure, you are blessed to have it!

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