Hi all. At first, sorry for my English) I had the same problem of consumption and heating - 1 hr of music in wired or bluetooth headset and my battery falls from 100 to 75% with considerably high heat. Phone Xiaomi Mi6 global, not rooted, remains screen-off all the music time. Chromecast off, autoscan off, PA lockscreen off.
A week ago I've turned off two settings that uses Headset Micro Service. And - the problem is gone for all week. I don't know if this is a general solution, but it seems to solve my problem.
Just for info, thanks.
And, of course - PA is a great player, especially with Hi-Res. Much thanks!