Noise is heard when connecting the amplifier board to the analog audio output of Apalis T30 + Ixora and playing the sound.
The noise sounds like quiet static, not a popping sound.
When you do not play any sound, you will not hear the noise you care about.
If you play back the system sound by clicking on the screen, you will hear it accompanied by noise together with the sound effect.
Even if the same amplifier board was connected to the analog audio output of Colibri iMX 6 + Iris, no noticeable noise was added.
This noise will not change even if the peripheral device connection is configured to the minimum.
I want to investigate what is the cause.