Thanks Felix, that sounded promising. I tried it with my new August EP650 Bluetooth headset, but stills skips on my One M8 using Rocket Player from music off the SD card, and that gives you the option to double the buffer size, but that didn't help. Interestingly, it plays fine on my Samsung Galaxy Tab S 10.5, also from music on the SD card. That doesn't have phone functionality of course, which means fewer background processes going on. I think it's probably a power saving issue, or possibly particular SD cards.
Here is solution. Btooth headset have 2 modes of playback: one is HQ audio, and the other is lower fidelity mode for phone calls. I noticed if Phone audio mode is disabled on my Arctic P311 headset, sound no longer skips anymore. View attachment 190818
I sincerely hope that my workarround resolved your audio issues.
-Greetings from Croatia!