Originally Posted by Albireo
Just out of curiosity: would this noise/distortion be volume-dependent, or constant at all volumes?

There is not a simple answer to this.

There are four different data formats the chips support. Those are set by two pins being either high or low. Just about everything uses either one of two of those formats.

If the actual data of the player is in one specific format and the chips misconfigure themselves for one specific format (out of the four) you could have the situation where the audio below about 6dB from peak would sound OK but would be swapped left to right and right to left. Audio within about 6dB from 0dBFS will digitally clip/distort. As I recall this is the audio data being in 24 bit left justified format but the chip is configured for 24 bit I2S is when this happens.

If the chip configures itself for either of the other two formats (both 16 bit settings) you will just get bad noise/distortion and of course the last of the four settings would be the correct one.

When I determine the format of the data I always test with a source that I know hits 0dbFS to determine if L/R needs to be inverted or if the data format is simply wrong. The 'My Disc' CD has a 1kHz test tone at 0dBFS which makes it really easy to hear if it is clipping or not.

Shawn

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