Questyle M15i — Mobile Headphone Amp & DAC

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.


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.


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

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.

Disclaimer

Questyle has kindly sent me their new, updated M15i in exchange for sharing my honest thoughts. Those who follow my reviews know, that they can only read my truthful findings, regardless of whether I can keep the product or have to send it back.



Intro & reviewer's background

I used to own the Questyle CMA600i and briefly the CMA 15. As an all-in-one solution I think Questyle units are great. Current amplification really has a unique touch to the sound and synergies especially well with planar headphones.
I use full-sized headphones and desktop gear; for a few years I have not really followed the portable market. I have no need for pricey portable gear as I do not commute to work and also throughout the years, I was fortunate enough to build up a fairly good home system with TOTL headphones. For those few flights a year I can manage with TWS earbuds for convenience as even a $1K portable solution would sonically be a compromise compared to my home system; ultimately it does not really matter whether I listen to a $200 TWS or $1000 DAP the compromises are audible. For this reason, I picked wireless comfort on my flights.
My last proper portable setup was the first gen. Chord Mojo and I cannot even remember what IEMs I used. The reason I am sharing this is to ask for excuse as in this particular review I won't be able to do many comparisons to similar devices like the Cayin RU7. I would still like to believe that my thoughts and experience could be useful to those who come from a higher-end home system trying to find an affordable portable solution.



Current amplification explained in a nutshell

There are two ways to amplify an electric signal: you can either amplify voltage which is the electrical force that drives the current between two points, or you can amplify the current which is the rate of flow of the electric charge. It is easier and cheaper to amplify voltage, that is why most amplifiers are built that way. The disadvantage of voltage amplification is more distortion. Current amplification on the other hand has physical limitations, it can only be done on more efficient headphone amplifiers and not on speaker amps. Amplifying current leads to a cleaner and less distorted signal, which is always beneficial. To my ears Questyle amps have a hint more realism versus similarly priced voltage amplifiers, which I believe is a result of this technology.



What is the M15i, what has been improved versus the M15 and my expectations

The M15i is a tiny, portable dongle DAC/amp based on Questyle's current amplification. The biggest update over the popular and original M15 is that the M15i now is fully MFi certified which means full and official Apple compatibility. The M15i also doubled on decoding performance; now supporting PCM 768kHz/32Bit and DSD512 as opposed to PCM 384kHz and DSD256 of the older model. Total harmonic distortion has also improved, from the already brilliant 0.00057% to 0.0003% for those number warriors.
I have not had a chance to test the M15i against the M15, but some claim a small sonic improvement while others say they sound identical. If you already had the M15 and do not own Apple devices, I probably would not rush to buy the M15i.



Build quality, usage scenarios

Build quality is excellent, as it is on all Questyle products I have tested so far. I really like the glass top, seeing the neat internals certainly contributes to the experience. The unit itself is surprisingly small, not much bigger than a USB stick. Carrying this little dongle DAC around is a lot easier than using any DAP or something like a Chord Mojo. I tried the M15i on my phone and with my laptop; it worked flawlessly in both cases as a plug & play device, no setup was necessary. I have to admit, coming from higher-end desktop systems my expectations were low. This tiny little device surprised me big time, not only sounding like an 'acceptable compromise' on the go, but driving my full-sized headphones to quite enjoyable levels.
I am still not a fan of using a dongle with my phone, as I find cables annoying and got used to the freedom and convenience of wireless earbuds on my flights. Where the big advantage of such a device lies for me is portable laptop use. You can just put the M15i in your pocket and take it with you to your favourite Café: work on your laptop and listen to good audio. It can also be a perfect little sound enhancer on your holidays in a hotel room, watching movies. The sonic improvements it brings to any laptop is huge.



Sound

Coming from multi thousand-dollar desktop systems my expectations were low regarding sound quality, yet the M15i surprised me with its full and natural sound and with the fact that it was able to drive my ZMF Caldera to good, quite enjoyable levels. For this I had to use high gain on balanced out and reach around 70% volume. In every case I found the 4.4 mm balanced out superior sounding to the 3.5mm single out.

Sound technicalities are good, exceeding my expectations for the $250 asking price. The sound is quick enough, natural enough, timbre and texture are surprisingly good and spatial qualities are also fine for a device in this category. My main point is that even coming from higher-end setups, the M15i did not leave me with the notion that some sonic qualities are painfully poor or missing. I did not only find the sound acceptable, but good: I was not only listening, but found myself enjoying what I heard.

Speed, soundstage, imaging is pretty much what you would expect with sub $500 devices, but I have never experienced such good sound in such a tiny chassis. I tried some Dragonfly dongles some time ago and have to say, the M15i is definitely a class above with its big, bold and more natural sound. It does not reach Chord Mojo 2's technical levels, but for the price it does not have to. Tonality is slightly warm, but in a natural way.



If I had to pick the most impressive part of the frequency range, I would say it is the bass. Bass is full, punchy, entertaining with good impact, but it is not overdone or overblown to bothering levels. There is a slight mid-bass emphasis, but it just tastefully enhances fun. When you are out and about it is actually handy to have a slightly stronger bass that balances out background noise.
Mids are nice and detailed enough, for this asking price I cannot complain much. As you spend bigger and bigger money, vocals can get sweeter and more lifelike, but mids are surprisingly natural for a little portable USB device thanks to the current amplification.
Treble is similarly fine, not bothering at all. It is more natural than what I thought it will be, highs are never piercing, never hot or overdone. Again, with much pricier devices you will get more space, more details more naturalness, but at this price it is a more than decent offer.



Finishing thoughts

I wish I had more dongle DACs around to give you a fuller picture of the competition, but I would consider the Cayin RU7 to be the closest alternative. Cayin also makes very nice stuff, so I hope one day I can check out their USB dongle as well and will be able to update this little write-up. For now, I can only say, even coming from much more expensive desktop setups the M15i did not disappoint. Sound quality, size, ease of use all contribute to the package which I found quite impressive for $250. Note, that you might have to pay import taxes on this depending on the country you live in.
While I personally find mobile phone usage a bit cumbersome, the M15i could well be your convenient laptop sound enhancer when you are out and about. I am planning to use it with my laptop when I am traveling. The sonic qualities Questyle was able to squeeze into such a tiny device is impressive. We truly live in a world of technical development. Well done Questyle, and thank you!

Preface:

I would like to thank @gadgetgod and Questyle for sending this unit as part of the review tour.

Also, I’m not a seasoned reviewer or a seasoned audiophile, so whatever I say are purely my observations and your results may vary.

I’m not the one to usually focus on specifications and numbers. I focus more on how happy I am with the equipment’s sound and that’s it.

Introduction:

Both versions of the M15 sound almost exactly the same. This makes sense because the M15i is meant to replace the previous model completely. It avoids having two very different versions of the M15 in circulation.

Specifications:

The M15i boasts impressive specifications that set it apart from conventional dongles. With a dynamic range of 130 dB and a THD+N of 0.0003%, it delivers unparalleled clarity and precision. Its output power can drive headphones ranging from 32 to 300 Ohms.

Frequency Response
±0.1dB (20Hz-20kHz) | ±2dB (20Hz-80kHz)
THD+N
0.0003 %
DAC
ESS flagship USB DAC chip ES9281AC

OUTPUT POWER

• 3.5mm:RL=300Ω | Po=11.97mW
  Vout (Max)=1.895Vrms
• 4.4mm:RL=300Ω | Po=22.6mW
  Vout (Max)=2.624Vrms

Physical Unit:

Crafted from CNC-machined aluminum, the unit exudes durability however the front glass is prone to scratches without the case. Its sleek profile and understated aesthetic makes it really cool to look at.



The transparent cover at the top provides a glimpse into the inner workings of the device, showcasing its high-quality components.




Despite its diminutive size, the M15i is packed with features. From the clicky and satisfying gain switch to the dual headphone jack outputs (single-ended TRS 3.5 and balanced 4.4 TRRS), every aspect of the unit is designed for convenience and versatility.

I hate having independent volume control. What I like the most in M15i is that I can control volume from my source than set the volume at the source and then use the dongle to change the volume.

The unit's USB-C port, located on the rear, allows for easy connectivity with a variety of devices, while the included fabric-jacketed Type C to Type C cable ensure reliable performance and durability.

It’s interesting to note that Questyle doesn’t include the lightning to type c cable when they’re marketing this as MFi certified dongle.

Overall, the Questyle M15i is not just a portable audio device—it's a work of art that combines form and function in perfect harmony.

Sound:

The sound quality of the M15i is nothing short of extraordinary. It offers a liquid, transparent, and high-resolution audio experience that transcends the limitations of traditional dongles. From the wide soundstage to the well-layered instrumentation, every aspect of the sound is meticulously crafted to provide an immersive listening experience.

Tonality and Timbre:

The tonality of the M15i strikes a perfect balance between warmth and neutrality, ensuring that every note is reproduced with utmost accuracy. Its timbre is rich and textured, capturing the nuances of instruments and vocals with remarkable fidelity. Whether you're listening to guitars, cellos, or vocals, the M15i excels in delivering lifelike sound reproduction.

Bass:

The bass performance of the M15i is nothing short of impressive. It offers a linear and impactful bass response, with quick and nimble transients that bring out the texture and detail in every note. From sub-bass rumble to mid-bass punch, the M15i delivers a satisfying low-end experience that complements a wide range of musical genres.

Vocals:

Vocals shine on the M15i, thanks to its smooth and full-bodied presentation. The vocals are positioned front and center within the soundstage, with a sense of depth and realism that makes them come alive. Whether you're listening to male or female vocals, the M15i ensures that every word is conveyed with emotion and clarity.

Treble:

The treble region of the M15i is detailed and nuanced, without ever veering into harshness or fatigue. It strikes a delicate balance between resolution and smoothness, ensuring that even the most intricate details in the music are preserved. Whether you're listening to classical or metal tracks, the M15's treble performance is sure to impress.

Conclusion:

In conclusion, the Questyle M15i is a game-changer in the world of audio dongles. With its exceptional sound quality, versatile connectivity options, and compact design, it sets a new standard for portable audio devices. Whether you're a casual listener or a seasoned audiophile, the M15i delivers a listening experience that is nothing short of extraordinary. With its unbeatable price-to-performance ratio, it's a must-have for anyone who values high-fidelity music on the go.