Questyle M15i x2 front and back quarter over white background
Questyle M15i top quarter over white background
Questyle M15i with attached headphone cable connected to iPad in human hand
Questyle M15i front closeup over dark background with gold circuits

Questyle M15i | Balanced Portable DAC and Amp

Regular price$249.00

Questyle logo black

M15i is the MFi Certified Update to Questyle's Beloved Ultra-portable Powerhouse

  • M15i boasts near universal compatibility with any mobile device or computer
  • 3.5mm and 4.4mm output with selectable gain, provides higher level of power for a wider range of headphones
  • Can handle up to PCM768kHz/32bit and DSD512
  • Optimizes power consumption to prevent premature phone battery drainage
  • Ultra-low noise floor of -130dB for a pure background and real sound

Questyle M15i with attached earphones connected to Macbook

Technology Without Boundaries

Questyle and ESS along with research teams in the United States, China, and Canada, maintain a continuous and fruitful collaboration to exceed customer expectations in mobile decoding headphone amplifiers. The M15i uses the updated ESS flagship USB DAC chip ES9281AC, supporting D/A converting up to PCM768 and DSD512 (1st Gen M15 supports up to PCM384 and DSD256). Audio distortion performance and output power have also been upgraded compared to the previous generation.

The original M15 was a best seller at Bloom and never actually experienced a slowdown in sales during its lifecycle. With the M15i, Questyle looks to expand its predecessor's popularity and bring and even higher tier of premium audio enjoyment in a portable form factor.

Hardcore Technological Aesthetics

The design of the Kunlun glass window coupled with the exquisite craftsmanship of the PCD, presents the critical elements of signal processing and technological aesthetics.

Questyle M15i x2 front and rear highlighting glass window and internal PCB

Apple MFi Certified for Guaranteed Performance and Compatbility

The "i" in M15i indicates that it has been certified by Apple's MFi. MFi certification ensures perfect support for iPhone/iPad and seamless integration into the Apple ecosystem. It complies with Apple's stringent requirements for external devices in terms of power consumption and compatibility, avoiding the risk of damage to phones and systems from arbitrary device pairings.

Patented SiP Current Mode Amplifier

The M15i contains two groundbreaking "current mode" patented amplification SiP modules developed by Questyle Technology. Overall, it totals four current mode amplification engines, delivering powerful and clear sound. Given that it operates in the current domain, the low impedance characteristics of the current-mode circuit result in a bandwidth of up to 1MHz and distortion as low as 0.0003%, capturing hidden details in songs.

As a result, the risk of overheating or interruptions during long listening sessions is extremely low thanks to the patented current mode amplification (TOREX precision power management technology) as well as the M15i's high performance and low power consumption.

Questyle M15i explosion highlighting TOREX component

Full Compatibility for True Lossless Enjoyment

During development, Questyle Labs conducted extensive testing and targeted optimization for M15i's compatibility with mainstream smartphones and tablets. Developers managed to achieve high compatibility with iOS, HarmonyOS, and Android versions 5.1 and above. As for PC, it supports Windows 10 18.3 and above (driver-free) as well as macOS. Hence, all HiFi headphone users can enjoy lossless audio on streaming platforms anytime, anywhere.

apps on multiple phones highlighting OS and streaming badges

3.5mm and 4.4mm Dual Ports with Gain Adjustment

The M15i, equipped with (x4) current mode engines, supports 3.5mm single-ended and 4.4mm fully balanced output modes. It also features manual gain adjustment, allowing users to choose the gain mode according to personal preferences, headphone characteristics, or the audio system, rendering the M15i suitable for a wide range of apps and devices.

Questyle M15i front quarter diagram highlighting manual gain switch

Dynamic Sampling Rate Display

When playing music, the data status indicator will light up.

  • A single red indicator means PCM data with a sampling rate not exceeding 48kHz
  • Dual red indicators represent high sampling rate PCM data or DSD audio data

Closeup active M15i connected to device showing dual red sampling indicators



  • Material: CNC machined aluminum
  • Color: Black
  • Size: 61.9mm x 27.9mm x 12mm

Compatible Operating Systems

  • Android phones and tablets: Android 5.0 and above
  • PC: Win10 1803 and above
  • Apple cellphone: iOS (You need to buy an OTG cable for Lightning to USB-C)
  • Apple computer: Mac OS

DAC Capability

  • PCM: PCM: 44.1kHz – 768kHz (16/24/32Bit)
  • DSD: DSD64 (1Bit 2.8MHz), DSD128 (1Bit 5.6MHz), DSD256 (1Bit 11.2MHz), DSD512 (1Bit 22.4MHz)

Output Power

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

Frequency Response & THD

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

In the Box

  • M15i Mobile Headphone Amplifier with DAC
  • USB Type-C to Type-C Cable
  • USB Type-C to Type-A Cable
  • Warranty Card
  • User Manual

Questyle M15i in the box

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Customer Reviews

Based on 1 review
Great value

This DAC amp is perfect for my portable uses or even if I want to use my headphones in a different room without having to be tethered to a desk.

Additionally they are really efficient with power consumption.

As for sound, sound is rather subjective however if I had to try and put it into words I would say it makes everything sound more full and more present so everything thing you love about your headphones you will continue to like as it will basically magnifies its existing qualities and brings them out even more. I tried it with focal clear "og" hifiman Arya organic, and Sennheiser hd600

Lastly any additional comments or potentially pros and cons

Pros I love the small form factor and simple design and is about the size of a pink school eraser

Only Con I can think of is I wish it had a little screen protector as I can picture the glass panel getting scratched or marked up over long periods of time but the see through look is the trade off as I think it looks cool.

Sorry for the long review just want to give buyers a little insight on the different features. Overall great product and is nice for both the size and price, I would recommend to people who are looking for something simple, easy to use, and don't mind taking places.

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