I've had a problem in the last 4 weeks ever since I started taking part in the Android 6 concept programme for the Sony Xperia Z3 line.
If I leave the equaliser turned on, horribly loud noise spikes destroy my listening experience. This happens with headphones and using the built-in loudspeakers. The Sony developers told us that the equaliser will be handled by the applications from now on instead of having a global equaliser for the whole system. This would mean that the problem is on your end.
Do you have any ideas, suggestions or work-arounds other than turning off the equaliser?
I've found reports of other people with the same problem asking for help, most of them months and years old. Are you aware of this at all?
Best wishes, Rustico
PS: Offline saving to SD-Card seems to be broken for Android M