Pros:
- Unique transparent design
- Outstanding neutral sound profile
- Hardware gain switch
- Powerful output
Cons:
- Quite expensive
- Tempered glass panel prone to smudges and needs extra care
Introduction:
Questyle is a brand from China that focuses on producing premium solid state amplifiers, digital to analog converters, and digital audio players. The AMP-CMA800 was their first product that was launched in 2012, and featured their patented Current Mode Amplification technology, which is different from the traditional amplifier implementation in other devices. The M15 is a sequel to the M12 which was launched in 2021, and now features a 3.5 mm single ended output, and a 4.4 mm balanced output. The M15 currently retails for 249 USD, and was provided to me for free by Questyle in exchange for this review.
Specifications taken from Questyle's website:
Sources:
Poco X3, Poco M3, Redmi Note 7 Pro, Redmi Note 10 Pro, Lenovo IdeaPad 110
Gears paired with the M15:
Headphones:
Koss Porta Pro
Koss KSC75X
thinksound ov21
SIVGA Phoenix
KLH Ultimate One
In-Ear Monitors:
Audiosense DT600
Audiosense DT300
Hisenior FE3U
Kinera Freya
NF Audio NM2
BQEYZ Autumn
Earbuds:
VE Monk+
VE Monk Lite 120
VE Monk SM
Vido
Astrotec Lyra Mini
HZSound Bell Rhyme
DQSM Z&W Panda
Test tracks:
Africano - Earth Wind and Fire
Dark Necessities - Red Hot Chili Peppers
Gurenge - Lisa
The Chain - Fleetwood Mac
Monsters - All Time Low
Ours - Taylor Swift
Stay - Mayday Parade
Snuff - Slipknot
Yesterday Once More - Carpenters
So Slow - Freestyle
Aurora Sunrise - Franco
Attention - Pentatonix
Blue Bird - Ikimono-gakari
You're Still The One - Shania Twain
Anyone Who Knows What Love Is(Will Understand) - Irma Thomas
Salamin - Slapshock
AOV - Slipknot
Hey Jude - The Beatles
The Way You Make Me Feel - Michael Jackson
...and a lot more.
Unboxing and Accessories:
The M15 comes in a fairly small black box. At the right side, there is a pull tab and the box opens up like a drawer. Upon opening, you will immediately see the instruction manual and the warranty card. Under the paperworks is the M15 itself sitting on a dense piece of foam. Underneath are two cables; one is a USB C to C cable for connecting the M15 to smartphones, and interestingly instead of a small adapter, a USB C to A cable for desktop connection.
Questyle also sent the dedicated leather case for the M15. This is sold separately and not included in the standard package. It comes in a basic sleeved box and includes a small drawstring pouch.
Build:
The frame is made of anodized aluminum. The most outstanding feature of the build is that there is a transparent glass panel that allows you to see all of the internal components including the ESS ES9281AC DAC chip and the amplifier circuit. Also visible are two LEDs. One for the gain setting (red for high, green for low), and another one for the data or the sampling rate of the file being played currently (green for 48 kHz and below, red for anything up to 384 kHz and for DSD, and magenta for MQA). This adds a unique touch to the M15 but of course, like all other dongles with a glass panel, it requires extra care and prone to smuges and scratches if handled carelessly. At the bottom portion, there are the 3.5 mm jack for single ended output, and 4.4 mm jack for balanced output. At the side, there is a switch for the gain setting, and finally at the top there is the female USB C port.
The cable is insulated with braided fabric and is quite stiff in comparison with the cables that other brands include. The housing of the connectors are made of plastic.
Now let's get to the sound.
Lows:
The lows have the perfect balance of being fun, yet detailed. The M15 provides excellent depth and decay in this region. Both the subbass and the midbass receive a very, very small bump that is almost unnoticeable in some tracks. Bass notes sound rather clean and organic, but at the same time each pluck of the bass guitar and each kick of the bass drum sound rich and full of energy.
Mids:
The mids are, what I would say, the most neutral section of the M15's sound. There is only a tiny lift in the upper mids most noticeable in the female vocals, but that's it. Everything else is reproduced with great balance in this region. String instruments are especially clear, with each pluck and strum being extremely detailed.
Highs:
The highs also have a nicely balanced reproduction. Upper section of the treble has great amounts of detail, with an average level of extension and never sounded grainy at all, while the lower section is solid and sufficiently provides needed sparkle in every track.
Soundstage and Imaging:
The M15's stage is slightly above average in the height and the depth alike. The clarity in the imaging is magnificent; it is able to depict each track in a distinctly analytical way yet does not lack in musicality at all. Each instrument is layered excellently and there is a very good amount of air in between them.
Comparisons:
Questyle M15 (ES9281AC, 249 USD) vs. Cayin RU6 in NOS Mode (Discrete R-2R, 250 USD)
The RU6 has more warmth in the lows. They are both superb in depth but the vibrations are a tad slower in the RU6. Transitioning to the midbass, still the RU6 sound a tiny bit richer. In the mids, both have outstanding clarity and maintains a neutral approach especially in the vocals, but then again, the warmth of the RU6 is still noticeable here, and becomes more evident when compared side by side to the M15. With the highs, the M15 has a bit more energy up top. The upper section has more air and extends partially longer in the M15. Details, especially the more subtler ones are also presented better in the M15. They are simply neck and neck in the technicalities. However, in the soundstage, the M15 partially extends more in the width, but they are virtually identical in the depth.
Conclusion:
Questyle has made something phenomenal here with the M15. The transparent design really makes you appreciate all of the tiny bits and pieces that contribute to the beautiful sound you will hear out of this dongle which, honestly, can effortlessly beat DAPs with a similar or even a higher price tag. Admittedly, it is a bit pricey but it will definitely make you feel like every single cent of hard earned money you put into it is worth it.