[dodap]

To test out one of my recent IEMs, a BQEYZ KC2, I tested it with a few new test files. Everything sounds ok but one file distorted heavily: an acoustic bass from Chesky Ultimate Demonstration Disc (can be found on Spotify).
To my surprise there are no distortions when I play this track on my Windows PC with this IEM. And it is nothing specific to either the IEM nor the Android device, my DAP has the same distortions with all the tested IEMs and Headphones.
What could be the reason for this strange behaviour?

 

[MindsMirror]

Try analyzing the file with MP3Gain or replaygain to see what the peak level is. Due to the way MP3s are encoded, it's possible for the decoded data to exceed the full scale level which may cause clipping depending on how the decoding and playback is handled. You can use MP3Gain to reduce the level of MP3 files without re-encoding, see if that fixes it.

 

[dodap]

MP3Gain gave me Volume 94,5 and Clipping Yes, Track Gain -6,0. But I still see no explanation, why my Topping DAC can handle the file but my Smartphone built in DAC chip and an attached Musiland DAC/Amp cannot handle this. (The file was downloaded from Spotify playing it.)

 

[MindsMirror]

"Clipping Yes" means that if the player decodes and sends the data to the DAC without reducing the volume first, there will be digital clipping in the signal. But if the player decodes the data to floating point and adjusts the volume before converting to fixed point data needed for the DAC, it may avoid the clipping. Your different players may handle this in different ways which could explain the different result. Now, I don't know for sure if this really is the issue in your case, but if you lower the volume with MP3Gain and it does fix it, then that would confirm it. Have you tried it?

 

[miketlse]

The answer is probably that you have two volume controls being used at the same time:

1. The first in your smartphone music player app
2. The second in your attached Musiland DAC/Amp

Try reducing the smartphone volume, and see if that cures the issue.

 

[dodap]

The distortion can still be heard even when the smartphone volume is only some 75% of the maximum volume.
It even could have something to do with the phone itself: It is one of those infamous Huawei/Honor devices, that notoriously do not support the USB file transport to an external DAC. At least with USB Audio Player Pro, my favourite app for Android music.