If whatever you’re doing works with av1 then I’d say go for it. I do AV1 for Plex since all of my devices can hardware decode, however I keep my own videos at h264 software encoded (for smaller filesizes) since Synology photos doesn’t support AV1.
I use tdarr for my large scale conversions to AV1 but I use shutterencoder for everything else. It’s like handbrake but friendly for working in large batches and the UI is really nice https://www.shutterencoder.com/en/
It will add H265 to the end of the name too
I use plexamp too with a large library so I can comment on the android side (I didn’t know some of these differences existed)
the app has settings for audio quality dependent on connection type, including not converting hires audio
as far as I can tell the EQ in plexamp is global across devices, though it has presets for specific devices
-same on Android I don’t think you can manually listen to downloaded songs outside of the app
I’ll also comment that I sort all my music by folder and Plex does ok with this
Not great, but it works
I’ve had one of these running for years, honestly I didn’t expect it to last this long as it looks really cheap