I have a 5.1 AVR (only AC3 / DTS capable) connected to my TV via ARC and I configured Plex to use audio passthrough.
It works perfectly but I have some weird issues for files played without transcoding (mainly AC3 files).
The audio volume is variable, especially for the voice channel. Every minutes, the volume is increased for some seconds and then it goes back to normal.
Surprisingly, there are no problems for transcoded files (E-AC3 to AC3).
Does anyone have also this problem ?