I recently installed the TVOS 27 Beta and there is a HUGE problem!
Stereo music is being forced into a multi-channel PCM stream, one my Denon AVR sees in a way that is not recognizable as stereo and does not allow up-mixing at all!
I have Continuous Audio Connection off, and have tried turning click and sound effects off (used to be OK), but the issue continues.
Send feedback to Apple:
https://www.apple.com/feedback/apple-music/
https://www.apple.com/feedback/apple-tv/