QUESTYLE M15i: A Progression From Its Antecedent

It's been a long time since I've reviewed a product from QUESTYLE as I'm quite eager to try on their latest offerings. QUESTYLE is considered as a respected boutique audio brand as their products are known to be well-made with excellent craftsmanship and it uses some finest materials and high quality components. This company is also quite innovative as they have some proprietary patents that will be their primary edge on audio technology that makes them even more credible in the eyes and ears of audio enthusiasts and audio professionals alike that truly elevated their status as one of the most excellent and revolutionary audio companies out there.

QUESTYLE M15 along with QP2R became one of my tools for conducting my assessment of audio products, and I owed my accomplishments and goals as an amateur portable audio reviewer. And now, QUESTYLE finally released a device that will be an improvement over the previous model.

Entering QUESTYLE M15i, the latest flagship headphone DAC/Amp dongle and successor of the highly-regarded M15. Like its predecessor, they share the same form factor, build profile and similar technology but QUESTYLE some features will cater more to modern audio needs as the audio technology keeps progressing.

On its overall build, it has a rectangular solid CNC-milled aluminium alloy with a total dimension of 16.8mm x 27.2mm x 12mm which is quite identical to its predecessor. Just like its precursor, it has a clear tempered glass provided by Kunlun which is known to be a provider of high quality tempered glasses on the screens of Huawei phones as we can see the inner workings of its circuitry with components like LED, transistors, capacitors, ICs and amplifier chips. In the side panel there is a manual gain switch to adjust either in standard gain mode or high gain mode. At its opposite ends, there we can find the USB type-C port and on the other part, two output jacks on its audio interface, 4.4mm balanced and 3.5mm single ended.

About its proprietary technology, The CMA (Current Mode Amplifier) is quite a wonder as I can attest with its technical performance. Once again, I will explain some details of this audio technology wonder, this is a SiP (System in Package) module with four working audio amplification engines that will function and deliver an excellent clarity, well-detailed, accurate reproduction and better power output for richer details and more vivid sound quality. It performs a similar performance peak of a Class A amplifier in which its core amplification is in the current mode of its circuitry due to the performance of it transistors, capacitors and with its discrete structure for better bandwidth and ultra-low distortion with total removal of those Transient Intermodulation Distortion (TIMD) a.k.a negative signal feedback. You can check out the more technical description about this CMA technology here

Along with its patented SiP amplifier, it was accompanied with another patented technology that is also co-developed with TOREX Semiconductor, a precision power management technology IC that handles the overall power management efficiently and also for better thermal management inside without possibility of interruption or overheating.

Like its predecessor, the QUESTYLE still implemented an ESS DAC, the flagship-grade ES9281AC on the M15i but it was upgraded with more power output, less distortion performance and better audio encoding. ES9281AC is more of a complete package of an audio IC as it also has its highly regarded SABRE9602 headphone amplifier that known its capability to deliver a good rating of Total Harmonic Distortion (THD) and remarkable Signal to Noise Ratio (SNR) for consistent performance at low power consumption. The encoding capabilities of the previous generation ES9281AC can process up to PCM 32-bit/384kHz and DSD256, and now with its updated model, it is greatly improved as it can handle up to PCM 32-bit/768kHz and DSD512.

M15i headphone amplifier dongle is quite easy to use as it is simply a plug-and-play device as we can connect it to other devices with USB type-C port like smartphones, tables and PCs. With MFi certification that this device was awarded upon, it can be fully-utilised its way in the Apple ecosystem while it is still able to maximise its compatibility in all hardware devices and software.

As for software compatibility, here is some information about its operation system requirements and the applications that will work on QUESTYLE M15i.

OPERATING SYSTEM	REQUIRED VERSION	SUPPORTING APPS
ANDROID	At least 5.0	UAPP(USB Audio Player Pro), HiBy Music, Onkyo HF, Neutron App
iPAD/iOS	At least iOS 8.4 (For Apple Music), need OTG cable for lightning to type on older iPhones	Apple Music
WINDOWS	At least WINDOWS 10 1083	Any music apps that supports USB audio access mode
MAC OS	It reported still works with OS X Yosemite	Apple Music and other music apps that support USB audio access mode.
LINUX OS	All distros (at least it works well with LinuxMint)	Any Linux music apps that support USB audio access mode.
HARMONY OS	Any music apps that supports USB audio access mode

The power output that this device have could deliver a strong amplification that it could even drive some of the most power-hungry cans out there and I assumed that all IEMs and earbuds are easy peasy on this one, so planar and ceramic drivers that are well-known to be stubborn to amplify on this regard will be driven properly. It delivers such a full-range response with a relative amount of dynamics and resolution on it.

As for power output rating, here is the following information.

AUDIO OUTPUT	RL LOAD	PO	VOLTAGE DIVISION
3.5mm single ended	300Ω	11.97mW	1.895Vrms
4.4mm balanced	300Ω	22.8mW	2.624Vrms

The QUESTYLE M15i doesn't have an independent hardware key volume buttons and built-in battery like its predecessor as it still relies on its host device for software volume control and a main source of its power output.

As for product packaging, it still has the same packaging box with the first generation, all contents are placed in an organised manner and here are the following contents:

• QUESTYLE M15i USB headphone amplifier
• Short nylon-braided type-C to type-C cable
• Type-c to type-A adaptor
• Paperwork like warranty card and instruction manual

Bonus:

• Brown leather sleeve for M15i

On its tonal performance, it appears that like its previous generation, it still retains that balanced-neutral sound that gives a crisp, detailed and highly technical albeit there are some very marginal differences in terms of power output and texturing.

The following IEMs that were used for testing this device:

• HIBY Crystal 6 Mk.II
• LETSHUOER CADENZA 12
• LETSHUOER EJ07M
• LETSHUOER EJ09
• LETSHUOER EJ07
• AFUL PERFORMER 8
• AFUL MAGICONE
• BQEYZ WINTER
• BQEYZ CLOUD
• KINERA IDUN GOLDEN
• TINHIFI T2 Mk.II
• TANGZU XUAN NV

LOWS/BASS:

This device could still deliver a well-balanced bass response  just like the previous M15 with excellent articulation, precise, clean albeit it is a tad more tighter and incisive. It will give that deep and reverberating feedback on its sub-bass presence from some sub bass-focused instruments octobasses, low octave double basses, low tone bass guitars, synthesisers and drum machines.

Mid bass can give a proportional texture on its note weight to some instruments and vocals even on some neutrally-tuned sets that I've tested. Bass guitars and double bass will have a rasping, resonant and sombre sound while bass kick drums will also have that resonant, thudding and rumbling sound on every kick as it executes well with some fast double bass drumming. And then, bass trumpets, they sound full and add some intensity with its dark timbre, and male vocals like bass and bass-baritones will have a more rumble on its depth and volume with their vibratos.

MIDRANGE:

It appears that it retains some of its predecessor's tonal characteristics as it has unquestionably one of the best midrange presentations on a headphone amplifier that this device could deliver. It furnishes a neutral, clean, clear and detailed sound on both vocals and instruments with some added sufficient warmth to give a more balanced sound.

Both male and female vocals have a sufficient note density on each vocal type with distinctive tonal characteristics.

Baritones - smooth, rich and velvety,

Tenors - dazzling, brassy and tad bright.

Countertenors - tender and coppery sound.

Contraltos - rich, strong and smoky.

Mezzo-sopranos - musky, graceful and emotive.

Sopranos - silky, gleaming and crystalline, it  can project a more spacious and better range of lyric and coloratura soprano vocals.

On instruments, they sound all natural to my ears as it is able to project some of its tonal qualities and timbre as they don't sound too coloured as it retains its accurate yet neutral tuning.

Strings:

Guitars - balanced to crisp and ceiling sounding on both acoustic and electric guitars.

Violins - vibrant, lively and eloquent sounding

Cellos - lustrous, sensuous and silky sounding.

Woodwinds:

Concert flutes - poetic, ethereal and rich sound.

Piccolos - clear, bright and whistling sound.

Clarinets - rich, mellow and brilliant sounding.

Saxophones - reedy, mild and sonorous.

Brasses:

Trumpets - metallic, full and vivid.

Trombones - tense, solid and rounded sound.

Tubas - hearty, ponderous and resonant.

Horns - mellow, resounding and velvety.

Percussions:

Snare drums - sharp, precise and hard hitting sound.

Tom-toms - it delivers a reverberating sound with ample warmth.

Tenor/Field drums - hard and sonorous sound

Kettledrums - it adds a more deep, resonant and rumbling sound.

Pianos - sort of well-balanced sound as it has some warmth with a hint of bright tone.

HIGHS/TREBLE:

It appears that the treble quality of the M15i is quite well-balanced and silvery smooth with a right amount of shimmer just to add some clarity on some vocals and more definition on attack of instruments.

The brilliance part of the treble region where this set is able to deliver a substantial amount of harmonics as it will give more air and considerably more sparkling on its overall sound if I used it on a set with either reference-neutral or neutral-ish-bright on their sound profile. Cymbals and hi-hats sounds are depicted realistically as it has a bright and sizzle sound on the cymbals while a short buzzing sound on hi-hats to give that distinctive chicky sound. Glockenspiels have those bell-like and silvery sounds while celestas have golden, sweet and lustrous sounds on them.

OVERALL TECHNICALITIES:

No doubt that this device is a truly a very technical one as it can be used as professional used on tracking and some basic mixing and also for analytical use for audiophile listening sessions. This device will project a fairly spacious sound field with impressive  well-defined layering of frequency and dynamic tones from each part of instruments with excellent separation in clean pitch black sonic canvas.

This device is exceptionally detailed and incredibly resolving in terms of resolution capability as it has a solid macro-dynamics with reasonable compression while it has a very sharp micro-detail retrieval as it can show some nuances and subtleties on an audio playback like notation attacks, vocal ends and that “roomy” effects.

PEER COMPARISONS:

QUESTYLE M15 FIRST GEN.

• It actually shares an exact form factor from features up to the build quality with its successor. The difference between them that this one doesn't have Apple certification (It wasn't that important to me at all to be honest) , a tad less power output compare to the current incarnation and the capability of the ESS DAC chip where this device can only encode up to 32 bit/384kHz and DSD256.
• While its share similar tonal profile which is a balanced-neutral sound but compared its successor, this one has a punchy bass response with more transparent and less warmth on its midrange and a tad emphasis on the treble in which the latter has a more tighter bass response, a bit more textured midrange and a slight attenuation on some parts of treble region while maintaining an airy extension and a tad more sparkle.
• As for technical performance, both M15 and M15i have almost identical performance in which the first generation has a noticeable sharper micro-detail definition.

AUDIOQUEST DRAGONFLY COBALT

• The premier headphone DAC/Amp dongle from Audioquest as it is still able to compete with other newer USB DAC/Amp dongles in the audio market in the premium range segment. Unlike the M15i, it has built-in volume button keys and also in a smaller form factor but its main connector is a USB type-A one as it was design to be used on laptops and PC and you need an adaptor to connect it with smartphones or other mobile devices which make this device a bit of a hassle to use.
• In terms of tonality, the Cobalt has a balanced-warmish tuning which is somewhat the closest thing on analogue-ish tuning which is a bit coloured sounding compared to M15i's analytical approach on crisp and detailed sound. That makes the Cobalt more aligned with a more musical and a bit fun tuning one as it has more punchy bass response, a warm midrange presentation and smooth but less airy treble sounding.
• As for its technical performance, AUDIOQUEST seems to put a limit on its built-in ESS DAC encoding capabilities of this device as it only can process up to 24-bit/96kHz but it also has power management IC from Microchip Technology Incorporated which also handle thermal control and power efficiency. While the COBALT appears to project a tad wider sound field but on other technical aspects, M15i is better.

LOTOO PAW S2

• Aside from PAW S1, I did test the PAW S2 last 2022 (Thanks Ted a.k.a Superchonk for the opportunity as he lend me his unit, Check out his youtube channel HERE) and it appears that it still retains some of the features of its predecessor, like an small LCD display for sampling indicator and other infos, a volume key button and even software EQ presets in which M15i doesn't have those features. It still uses a reliable AKM DAC but its decoding on audio format performs less compared to the improved ESS DAC of the M15i.
• It seems that it has warmish-neutral sound profile that will be more appealing to analogue-ish type of tuning which has warmth and smoothness which is quite a contrast compared to the M15i which is leaning towards more analytical and way more technical sounding in which it is more align with balanced-neutral and reference-neutral type of sonic profile. It has more punchy bass, more textured mids and smooth but less airy treble (the stock tuning).
• On technical aspects, the encoding performance of AKM DAC on PAW S2 in terms of audio format support seems to be dated on paper as it can only decode up to  32bit/384kHz on PCM and DSD128 on DSD format. For sure that it can project a fairly spacious sound field and almost holographic stereo imaging but on other aspects like layering, separation and resolution capabilities, it is less crisper, less clinical and less resolving if it was compared to M15i.

To put a conclusion on this review, it seems that QUESTYLE capitalised the success of the M15 as this device still inherits those aspects that makes this device has its own merits in terms of improvement. While it still retains the construction profile of the original, The M15i has some noticeable improvements like an upgrade on encoding of audio support formats and a tad more power output.

But the big question that will be raised among audio enthusiasts,”how does it compare to the previous M15 and should we still purchase it considering that we still have the M15 first generation?”. Well, If you already have the M15 first generation, you can simply skip it but if you are looking for more power output, improve audio format encoding support and a MFi-certified device that will support all Apple devices, on the other hand, if you want to purchase your first QUESTYLE product which is quite highly capable for audio portable usage or simply want to add as part of your audio gadget collection, I will fully suggest that you should try this one out and enjoy its tonal performance.

QUESTYLE M15i is now available at QUESTYLE OFFICIAL STORE. If you are interested to check out more information regarding this product, simply click the unaffiliated link below.

★★QUESTYLE M15i - OFFICIAL STORE★★

Also you can check my previous review on QUESTYLE M15 in the link below that I've provided.

■ QUESTYLE M15

PROS:

● Still retains the overall construction of its preceding model.

● Solid aluminium alloy on its chassis while maintaining a good weight and compactness.

● A tempered glass panel is quite appealing to some audio enthusiasts who are either technical or simply love its glass panel as it showcases some of the inner workings of its circuitry and components.

● Detachable type-C cable connector.

● Manual toggle switches

● Two audio interfaces, 3.5mm and 4.4mm balanced.

● It has substantial software support and is compatible with all devices in either mobile or desktop.

● An improvement of audio support encoding on both PCM and DSD formats from its upgraded ESS DAC.

● A slight enhancement of power output delivery.

● Neutral sound and still has an impressive technical sounding.

CONS:

● Still doesn't have volume key buttons.

● Not for audio enthusiasts who are seeking a more analogue-ish type of tonality.

● Absence of built-in battery.

Tracks Tested: ( * = 16-bit FLAC, ** = 24-bit FLAC, *'* = MQA, '*' = DSD, *'= .WAV)

Alison Krauss -When You Say Nothing At All *

Jade Wiedlin - Blue Kiss**

Led Zeppelin - When The Levee Breaks **

Mountain - Mississippi Queen *

Queen - Killer Queen **

Guns N' Roses - Patience *'*

Eric Clapton - Tears in Heaven '*'

Sergio Mendes- Never Gonna Let You Go '*'

Pearl Jam - Daughter **

Roselia - Hidamari Rhodonite *

Assassin - Fight (To Stop The Tyranny)*

Celtic Frost- Visual Aggression *

New Order - Blue Monday *

The Corrs- What Can I do (unplugged version) *

Jimi Hendrix Experience - Voodoo Child *

The Madness- Buggy Trousers *

Metallica - Motorbreath **

Mariah Carey- Always Be My Baby *

Destiny's Child - Say My Name *

Malice Mizer- Au Revoir *

Mozart - Lacrimosa *

New York Philharmonic Orchestra - Dvorak- Symphony 9 " From the New World." *

Eva Cassidy - Fields of Gold (Sting cover)*

Michael Jackson - Give In To Me *

Exciter - Violence and Force *

Diana Krall - Stop This World **

Debbie Gibson - Foolish Beat *'*

The Sisters of Mercy – Lucretia My Reflection**

Suzanne Vega – Luka **

Lauren Christy – Steep *

Ottoman Mehter - Hucum Marsi *

Diana Damrau - Mozart: Die Zauberflöte*

Type O Negative - Black No.1 *

Felix Ayo - Vivaldi: Presto **

Three Tenors - Nessum Dorma *

Mercyful Fate - Witches' Dance *

P.S.

I am not affiliated to QUESTYLE nor receive monetary incentives and financial gains as they provide me a review unit for an exchange of factual and sincere feedback from yours truly.

Once again, I would like to send my gratitude to Mr. Zach Bielak providing this review unit. I truly appreciate his generosity and trust towards me and other reviewers.