[popcornmix]

haven't tried it without the 2 last lines.
first i tried it with fiq_enable=1 and changed also the fsm_mask 0x7 etc. always crackling sound
and when i set fiq_enable=0 it worked :-)
if I have time I'll try it and a few other things, which were mentioned in the Volumio forum. they fixed it already and i'm trying to find out how :-),

Remove the last two lines (shouldn't make a difference).
Remove all the lines and report what happens.
Try just adding: dwc_otg.fiq_fsm_mask=0 and report.