Disclaimer
- The review item is a sponsored tour unit from Questyle. All opinions remain original ideas of my own, there was zero influence from any 3rd party or external opinions throughout the review.
- No EQ or filter presets were used during the entire sound evaluation.
- Sound evaluation are kept neutral and does not include 3rd party accessories (ie; filters, eartips, cable, irreversible/reversible mods)
Pros
- Excellent build quality, the iconic M15 platform.
- Tactile, intuitive interface/controls.
- Capable of providing a good amount of output especially through 4.4mm balanced.
- Physical hardware tuning based on preference, though both mainly adds warmth from the bass as well as adding smoothness in the midrange and treble.
- Enhances clarity and resolution (especially Blues Blue).
Cons
- Faint background noise on both units.
- Slightly less airy and soundstaging width with the Electro Purple.
Introduction
Questyle’s M15 series has long been a benchmark for what a portable dongle DAC can achieve, thanks largely to their patented Current Mode Amplification (CMA) technology. However, the release of the M15i Electro Purple and Blues Blue editions marks a fascinating pivot for the brand. Now providing customers a change from the neutral reference sound which we all know from Questyle to a tuning that caters specific musical tastes such as Blues, Jazz, and EDM through an advanced process of physical hardware tuning.
Maintaining the iconic transparent glass chassis but sporting vibrant new anodized finishes, these “i” variants (Apple MFi certified) promise to deliver more than just a cosmetic face-lift to justify the price increase. By tweaking internal components rather than relying on digital EQ, Questyle aims to enhance subjective qualities like density, layering, and spatial imaging as what they have promised inside the marketing. Today, we’re looking at how these two colorful siblings perform and whether this hardware-tuning approach truly elevates the legendary M15 platform.
Packaging and Accessories
Questyle has kept the same packaging to the original M15i with these newer versions of dongles. It features this compact hard box with Questyle’s distinctive monochromatic designer-like packaging that shows a diagram of the product, in this case the M15i. Other than that, it’s pretty standard, you’d get your basic information and specification of the M15i scattered around the packaging.
Upon opening the box, on the first tier you’ll be greeted with a copy of the user manual and a warranty card, the M15i dongle itself and lastly at second tier there you’ll find all the accessories such as a USB type-C to type-C cable as well as a USB-A to USB type-C adapter to connect the M15i to your laptop or other devices that use the corresponding connection.
Design and Ergonomics
“If it ain’t broke, don’t fix it”, that is what can be said when it comes to the M15i design. Questyle have utilized the same chassis design of the original M15 with very few cosmetic updates, the most obvious one is the brand new colourway which is the Electro Purple and Blues Blue version finished in anodized finishing to achieve a fine, very smooth brushed look and texture. Like the original M15, Questyle still kept the viewing glass panel to show the various internal components and circuitry inside the dongle all gorgeously displayed.
Overall construction of the M15i feels robust and weighs substantially hefty considering it is mostly made of metal, the buttons feel tacky and solid. I could not hear any sort of rattling to the components inside the dongle including the 4.4mm balanced and 3.5mm jack and the switch for high and low-gain settings. Everything feels well-made and feels high-quality which is what Questyle is known for with all of their products. In terms of ergonomics, the M15i remained the same. All the controls are intuitive and easy to reach, it requires a bit of force to push/pull the high/low-gain switch to prevent any accidental cause if you intend to carry the M15i inside your pocket. Although I do feel that the gain setting switch is placed a tad too flushed especially for those who have large thumbs.
Features
The biggest update that makes the new Questyle M15i Electro Purple and Blues Blue version a lot different than the original M15 and M15i is the implementation of physical tuning rather than relying on equalization (EQ) or any software to achieve a sound profile that’s suited for Blues/Jazz and EDM. Similarly to how audiophiles swap components such as op-amps, etc to achieve a different sound profile and enhancement. Therefore, this is a much more complex, technical and more cost consuming method compared to tweaking through software. This way as Questyle claimed, they could achieve more than what EQ could do such as subjective qualities such as layering, density, spatial imaging, etc without altering objective measurements compared to its predecessor.
Apart from that, the M15i Electro Purple and Blues Blue adopted the same features to the previous M15i including the main hardwares, such as the ES9281AC DAC chip from ESS SABRE, two units of Questyle’s patented CMA (Current Mode Amplification) and of course the TOREX Precision Power Management System that provides impressive measurement numbers. Therefore, it can be said there is no objective number increase/decrease with the new update compared to the previous model, the 2.6 Vrms output power from the 4.4mm balanced and 1.89 Vrms on 3.5mm can provide more than enough power for most IEMs. Albeit I do notice there is a very faint humming noise in the background, especially with high sensitivity IEMs. The previous M15i variant had also been reported to have this problem, therefore I suspect Questyle have yet to entirely solve this issue.
Specifications
Visual Appearance
- Material: CNC Aerospace-grade Aluminum Alloy
- Color: Electro Purple, Blues Blue
- Size: 61.8mm x 27.2mm x 12mm
Compatible Operating Systems
- Android phones and tablets: Android 5.0 and above
- PC: Win10, ver. 1803 and above
- Apple: iOS (Requires OTG cable for Lightning to USB-C)
- Apple Desktop/Laptops: Mac OS
DAC Capability
- PCM: PCM: up to 32-bit 768kHz
- DSD: up to DSD512 Native
Output Power
- 4.4mm (300 Ohms load): 22.6mW (2.624 Vrms)
- 3.5mm (300 Ohms load): 11.97mW (1.895 Vrms)
Frequency Response & THD
- Frequency Response: ±0.1dB (20Hz-20kHz); ±2dB (20Hz-80kHz)
- THD+N: 0.0003%
- DAC: (2x) ESS SABRE ES9281AC
Sound Evaluation
Sound evaluation was done by pairing both Questyle M15i with my reference in-ear, Audio Technica ATH-IM02. Alongside other IEMs to see whether there are sonic changes or effects caused by the source to my IEMs. Hence, resulting in a shorter narrative compared to my usual sound evaluation to other equipment. This is a purely subjective opinion, based on what I hear and experience as well as my bias.
- Electro Purple
The M15i Electro Purple offers a rich, lively and engaging experience when paired with my ATH-IM02 throughout the testing period. The most immediate characteristic that I was able to notice is the sub-bass, it provides a more prominent, slightly more aggressiveness in the rumble with a noticeable reverberation effect that adds a sense of depth to the low end especially in songs such as Hollow (16 bit Remix) – Björk. Bass slam in the ATH-IM02 sounded much thicker and carries a heavier, heftier thud when compared to a much neutral source. Although with the cost being the transients are slightly slower, giving the low-end a more deliberate and visceral presence rather than a fast and abrupt tail between each bass slam. This colouration carries over into the lower-mids, which sound smooth and wonderfully rich, though it does make the ATH-IM02 feel somewhat recessed in presence, placing the listener a few rows back from the center stage. Therefore, if you already have a coloured sounding IEM, the M15i Electro Purple might elevate the intensity slightly more.
While this combination manages to keep the highs stay crisp and lively, the higher frequencies sounded slightly subdued and rounded off, ensuring a fatigue-free listen at the cost of some sparkle and brilliance. However, the resolution and detail retrieval are slightly inferior but nevertheless the focus here is clearly on tonality and weight rather than surgical precision that you’d get from a reference, neutral source. Other than that, the dongle also alters the soundstaging in my ATH-IM02, it felt more intimate and slightly boxy rather than expansive, added with lack the airiness that allows for a wide-open holographic image. However, for those who value a thick, musical, and warm presentation over raw technicalities, the M15i Electro Purple provides a very satisfying and grounded listening experience.
- Blues Blue
The M15i Blues Blue presents a more technical and airy alternative, delivering precision and spatial clarity into the ATH-IM02. The bass still remained on the leaner side but with a tad slower transient response which I appreciate especially for an all balanced armatures setup. Bass slams remain punchy and agile that resembles a thud but it feels a tad richer, a touch more depth. Subtle sub-bass rumbles and reverberations are slightly more enhanced as I noticed that the ATH-IM02 could render subtle textures and small nuances in sub-bass rumbles. The midrange is where the Blues Blue truly excels, the synergy with the ATH-IM02 made the midrange on this IEM sounded smooth and even more lush benefiting from a noticeably darker background that allows for better articulation especially for vocals and stringed instruments There is a slightly more prominent upper-mid presence that adds a sense of clarity and pushes vocals a bit more forward, though it remains controlled and never approaches a shouty or fatiguing territory.
The treble response with this dongle is a tad brighter with a stronger presence which is what is needed on the ATH-IM02. Additionally, the treble has a bit more crisp, energetic feel especially with elements such as hi-hats and crashes. Unlike the Electro Purple which has a more intimate soundstage, the Blues Blue offers a large, expansive soundstage with a generous sense of air surrounding each instrument. Layering and separation on the ATH-IM02 were also enhanced, vocals and instrumental elements feel distinctly separated and individually placed within the sound field, making it much easier to track complex arrangements.
Comparison(s)
- Questyle M15
Comparing both newer versions to the original M15, the Blues Blue enhances the mid-bass to provide a much fuller, meatier bass slam. Although it is not as exaggerated as the Electro Purple which provides an overall greater amount, heavier, thicker bass quantity and experience. Meanwhile in terms of sub-bass, Blues Blue had the best balance between being able to enhance texture and clarity rendering rumbles/reverberations over the original M15 which was too flat in my opinion. The Electro Purple is slightly muddy in contrast, although it does enhance sub-bass performance slightly greater than the Blues Blue.
Midrange sounded the best with the Blues Blue as well, compared to the original M15 and lastly the Electro Purple. It was lush, natural and definitely enhanced vocal and instrument presence, resulting in a much forward yet still butter smooth presentation with very good clarity. The Electro Purple made my IEMs sound slightly veiled which I’m not quite fond of, however if you do like your midrange very coloured and a slightly less intense upper-mid this dongle might be a good pairing with your IEMs. Despite that being said, the M15 still has its rightful place of its own providing a flat, uncoloured midrange. The only difference I could hear through my IEM paired with the M15 was the upper-mid now sounded slightly smoother with a darker background.
Treble sounded the liveliest with the Electro Purple, however it does get slightly tizzy and slightly sharp when paired with my ATH-IM02. Compared to the other two, Blues Blue sounded the most balanced, most engaging, clear and crisp treble meanwhile the M15 has slightly less treble presence but still can provide a crisp and lively sound, both without any sort of sibilant. Therefore, if you like unaltered reference sound, the M15 would be suitable. Meanwhile, the Electro Purple is more towards those who like it, fun and lively with the hard, meaty punching bass and Blues Blue sits right in the middle, which strikes the perfect balance between reference precision and musicality.
Purchasing Links and Where to Get?
Questyle Official Website (non-affiliated)
Conclusion
The Questyle M15i Electro Purple and Blues Blue editions represent a bold experiment in digital audio. Rather than giving the user a flat canvas, Questyle has provided a curated experience for audiophiles to let them choose what’s the best to be paired with their setups.
In short, the Electro Purple is a bass-lover’s delight, offering a visceral, thick, and non-fatiguing sound that prioritizes feeling more than just hearing every micro-detail which most true-blooded audiophiles are most keen. On the other hand, the Blues Blue is arguably the star of the show for the critical listener or probably for someone who just wanted a dongle that will work for literally everything and still sounds magnificent. It strikes a masterful balance between the original M15’s precision and a newly found sense of air, lushness, and spatial separation. Although these dongles do not make your IEMs sound signature change night and day into a whole different sounding earpiece, the difference is quite obvious.
While the hardware update doesn’t change the objective power specs, the subjective shift is undeniable. If you found the original M15 a bit too clinical or flat, these new iterations offer a way to inject personality back into your chain. For those seeking the balance of musicality and technical prowess, the Blues Blue is an easy recommendation. It’s simply the M15 and M15i sound, just a little more grown-up and refined but if you prefer to keep your sources neutral, I’d still think the old players are more than capable to be the source of your muse.