I've sent a build (see PM) for you (who posted in this topic) which detects killing by battery optimizer and also improves jumping over unplayable/missing files (these will stop playback in build-814) + few device variants quirks. Generally, for 814 audio may stop: (90% of cases) when killed by (e.g. Xiaomi, Sonys, etc.) battery optimizer (Unlocker is killed too with whole Poweramp and should be set to No restrictions too (wording is different across MIUI variants) in Installed Apps).