Do you understand my problem?
I have the SAME issue at M7, M9 AND M11. Different devices, different situation, different storage, SAME manufact., SAME chipset, SAME FiiO app! AND tada,there are NO problems with other devices....
The SD cards are working fine. The headphones are working fine (same model) and so on...
I tested it with Neutron again - ~60 min with different tracks, different time.... no problems with micro gaps. It seems, FiiO designed the FiiO music app NOT only for ONE model just for all the models of the same range (M range). That's the reason why the issue reproduces at all M devices....
FiiO has to design a single app for every model!
A normal 3rd party app will have the same problem - my preferred gonemad player reproduces the same error - it's not adapated to this model.
Neutron does not reproduce this issue, it's seems it's adapated to the M11 model (as discussed in Neutron forum)....maybe some hardware settings have to adapt (latency for example)....
It seems Samsung's SoC / BT chip is not really working with standard settings....