Questyle M15i — Mobile Headphone Amp & DAC

General Information

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Questyle M15i

The Questyle M15i is the second-generation, MFi-certified update to our award-winning high performance portable M15 DAC/amp.

  • 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 ultra-low distortion levels of 0.0003%

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Supports high resolution sound
The M15i features the highly acclaimed ESS ES9281AC flagship DAC, which can handle up to PCM768kHz/32bit and DSD512. It’s almost inconceivable that something as small as the M15i can process and reproduce such demanding audio formats.


MFi certification
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 iOS and macOS ecosystem. It complies with the stringent requirements for external devices in terms of power consumption and compatibility, avoiding the risk of damage to phones and systems from arbitrary USB device pairings.

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Dual headphone outputs
The M15i, equipped with four current mode amplification 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, making it suitable for a wide range of apps and devices.

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Full Compatibility for True Lossless Enjoyment
During the development, Questyle Labs conducted extensive testing and targeted optimization of M15i's compatibility with mainstream smartphones and tablets. Developers managed to achieve high compatibility with iOS, HarmonyOS, Android versions 5.1, etc. As for PC, it supports Windows 10 version 18.3 and above (driver-free) as well as Mac OS systems. Hence, all Hi-Fi headphone users can enjoy lossless audio on streaming platforms anytime, anywhere.

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Powerhouse Current-Mode Amplification
The M15i contains two groundbreaking "current mode" patented amplification SiP modules developed by Questyle Technology. Given that it operates in the current domain, the low impedance characteristics of the current-mode circuitry result in a bandwidth of up to 1MHz and distortion as low as 0.0003%, capturing details hidden in the soundtracks. As a result, the risk of overheating or interruptions during long listening sessions is extremely low thanks to the patented current mode amplification, TOREX‘s efficient power management system, as well as the M15i’s high-performance and low-power consumption.

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Comparison to predecessor M15
M15iM15
Apple MFi certification, ensures high performance and compatibility with iPhone/iPad and the Apple ecosystemno Apple MFi certification
supports up to PCM768 and DSD512supports up to PCM384 and DSD256, plus MQA support
Data status indicator:
1)single red indicator lights up means sampling rate≦48Khz
2)dual red indicators lights up means sampling rate >48Khz
Data status indicator:
1)green indicator lights up means sampling rate≦48Khz
2)red indicator lights up means sampling rate >48Khz
3)magenta indicator lights up means MQA mode sampling
Gain status indicator:
1)single red indicator lights up means Standard Gain
2)dual red indicators lights up means High Gain
Gain status indicator:
1)green indicator lights up means Standard Gain
2)red indicator lights up means High Gain

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Specifications

Compatible Operating Systems
  • Android Phones and Tablets: Supports devices running Android 5.0 and above
  • PC Systems: Compatible with devices running Windows 10 version 1803 and above
  • Apple Phones: Supports iOS systems (Requires additional purchase of the Questyle LTC02 Lightning to Type-C adapter when connecting to devices with a Lightning interface.)
  • Apple Computers: Compatible with macOS systems

D/A Conversion
  • 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)

Outputs
  • 3.5mm single-ended headphone jack
    • RL=300Ω,Po=11.97mW, Vout(Max)=1.895Vrms,THD+N=0.0003%
  • 4.4mm balanced headphone jack
    • RL=300Ω, Po=22.60mW, Vout(Max)=2.624Vrms, THD+N=0.0003%
  • Frequency Response: ±0.1dB(20Hz-20kHz); ±2dB(20Hz - 80kHz)

External
  • Exterior Material: CNC Anodized Aluminum Alloy
  • Color: Black
  • Dimensions: 61.9L X 27.9W X 12D(mm)

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What's In The Box
  • M15i USB DAC Headphone Amp
  • Type-C to Type-C cable
  • Type-C to USB-A Converter
  • User Manual & Warranty Card

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Where to Find

— From Shenzhen with ❤️
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Comments

macaddicted

Head-Fier
Got mine. I have an M3X, which I like a lot, but couldn’t find an android music app I was comfortable with, so it is largely unused. Yes, after 25 years, I’m fully enclosed in the Apple walled garden; four devices go off when I get a phone call.

I wish I could give more of a full review, but I don’t have much experience beyond the Shanling, and my absolutely preferred phones are Blessing 3 on a balanced cable. What I like with the M15i is I can plug it in to my iPhone and listen to any of my playlists, as I have since iTunes first came to the phone.

So, the sum of my review:
Both lights come on when I stream lossless music from Apple.
 

Pretardo

100+ Head-Fier
What's the battery drain like with the M15i? I had a HIby dongle dac that I used for about a week because it was a battery hog and I was worried that I was going to hobble my iPhone battery prematurely.
 

Uberding

Head-Fier
What's the battery drain like with the M15i? I had a HIby dongle dac that I used for about a week because it was a battery hog and I was worried that I was going to hobble my iPhone battery prematurely.
Battery drain is the lowest I’ve seen with any of the 5 dongles I’ve had.
For example with iPhone 15 Plus, starting at full charge and using Roon, my RU7 will drain the battery in about 5-6 hours.
With M15i after about 6 hours of use the battery was still at 65%.

FYI: For dongles I use this cable with a MagSafe battery pack that also has USB-A out.
iPhone battery optimization is set to 80% charge limit so no worries.
https://ibasso.com/product/cb19/
But the M18i is so efficient I probably won’t bother when using that one.
 
Last edited:

Pretardo

100+ Head-Fier
Has the M15i fixed the RF interference propensity from the previous M15 version?
That’s a deal breaker right there for me. RF noise for a phone dongle is really annoying. Were there any reports of noise on the M15/i using the Questyle lightning to USB-C cable or was it a different cable?
 

Pretardo

100+ Head-Fier
Battery drain is the lowest I’ve seen with any of the 5 dongles I’ve had.
For example with iPhone 15 Plus, starting at full charge and using Roon, my RU7 will drain the battery in about 5-6 hours.
With M15i after about 6 hours of use the battery was still at 65%.

FYI: For dongles I use this cable with a MagSafe battery pack that also has USB-A out.
iPhone battery optimization is set to 80% charge limit so no worries.
https://ibasso.com/product/cb19/
But the M18i is so efficient I probably won’t bother when using that one.
Thanks for letting me know. That’s pretty awesome that the M15i is so efficient. ! My first foray into third-party hi-if dongles was a shock. I was hoping to move away from carrying a DAP and a phone to keep my EDC light. But I was shocked by how much balanced dongles drained my phone’s battery. It kind of kept me off of them and into DAC/AMPs.
 

Uberding

Head-Fier
That’s a deal breaker right there for me. RF noise for a phone dongle is really annoying. Were there any reports of noise on the M15/i using the Questyle lightning to USB-C cable or was it a different cable?
I get a bit of RF interference.
Not often though: A 1 second or less pulse of white noise in the background.
iPhone 15 Plus cabled with ddhifi TC07S.
This is worrisome as I’m trying to move away from DAPs to simplify things and also because both my DAPs pick up crazy amounts of RF noise when travelling.
As soon as we reach the point where there is no wifi or cell signal and everyone’s phones start searching for service they become basically unusable.
I haven’t left the house with the M15i yet.
 

Pretardo

100+ Head-Fier
I get a bit of RF interference.
Not often though: A 1 second or less pulse of white noise in the background.
iPhone 15 Plus cabled with ddhifi TC07S.
This is worrisome as I’m trying to move away from DAPs to simplify things and also because both my DAPs pick up crazy amounts of RF noise when travelling.
As soon as we reach the point where there is no wifi or cell signal and everyone’s phones start searching for service they become basically unusable.
I haven’t left the house with the M15i yet.
I've had the same issue. I found that the headphone cables also made a difference with RF noise. The solution that I've come up with is to go for Bluetooth DAC/AMPs. I've found that they are really good at keeping a low noise floor even though they need to pick up wireless signals. I currently have a Shanling H5, Fiio BTR7, and Qudelix 5K. Each of them is dead quiet even when in the same pocket as a phone.
 

Uberding

Head-Fier
I've had the same issue. I found that the headphone cables also made a difference with RF noise. The solution that I've come up with is to go for Bluetooth DAC/AMPs. I've found that they are really good at keeping a low noise floor even though they need to pick up wireless signals. I currently have a Shanling H5, Fiio BTR7, and Qudelix 5K. Each of them is dead quiet even when in the same pocket as a phone.
Appreciate this.
I never noticed my DAPs being unusably noisy (on planes or ferries) when I first got them.
But now that you mention this it’s occurred to me I have different IEMs now.
So I’m wondering if it’s the IEM cable?
Just switched cables. We’ll see how it goes. Thanks.

And to be fair to Questyle: With the M15i I’ve only experienced a total of maybe 2 seconds of RF noise in 40-50 hours of use. And this is with the IEMs I now suspect have a noisy cable.
 

Pretardo

100+ Head-Fier
Appreciate this.
I never noticed my DAPs being unusably noisy (on planes or ferries) when I first got them.
But now that you mention this it’s occurred to me I have different IEMs now.
So I’m wondering if it’s the IEM cable?
Just switched cables. We’ll see how it goes. Thanks.

And to be fair to Questyle: With the M15i I’ve only experienced a total of maybe 2 seconds of RF noise in 40-50 hours of use. And this is with the IEMs I now suspect have a noisy cable.
I used to live in Hong Kong and the amount of RF noise that some DAPs received and passed on through the chain was horrible, especially in very crowded areas with lots of WiFi, cell towers and just tons of phones everywhere. I’ve had to play around with different cables and devices and found that one cable can make the enjoyment of music on the go plummet.
Let us know if the cable helps reduce the noise and if it’s single ended or balanced. That picks up RF noise. I had a Hiby R6pro and the single ended was great, but the 4.4mm port picked up noise no matter what I did.
 

AleksanderWWA89

New Head-Fier
Hey guys, I need your help. I'm trying to decide between two devices and I'm wondering if there's any reason to pay almost double the price for one of them. Specifically, I'm considering buying the M15i, but I can't justify the high price tag compared to the Fiio KA17. Can anyone offer any insights or recommendations?
 

faremissound

New Head-Fier
Hi! Has anyone here tried M15i with highly sensitive IEMs, such as Campfire Andromeda? Specifically I’m curious about the background noise (hiss) often being an issue with these particular iems. Thanks!
 
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