Many of these phones can only send AAC or SBC over bluetooth to other devices.
The choke point could be around there.
The choke point is that regardless of what CODEC I select on the AP80 and the S7 Edge, once I hit "play" on the latter, the AP80 displays LDAC then nothing actually goes through. That's already on developer mode where I can manually order the S7 Edge to just only do SBC or AAC or Apt X, despite LDAC being an option.
Just out of trial and error I discovered that the only config that works is "LDAC Standard" on AP80 with "LDAC, Balanced (SQ and Connectivity)" on the S7 Edge.
The weird part really is why the AP80 overrules what I set it to other than LDAC as the S7 Edge, when I check, doesn't change which CODEC it's using when it doesn't work. It is only on the AP80 that the displayed CODEC suddenly turns into LDAC with the S7 Edge regardless of what was on the screen before I played music.
The same issue doesn't happen on the S9 and Windows laptop.
* maybe a usb c to usb c might solve it also. ddhifi has a good one.
Ergonomically doesn't work for my use case as I got the AP80 so that I can wireless control its playback of music on its SD card (mostly at home so I can hook up the AP80 to my desktop amp and set the output to fixed 2V) or stream Spotify to it from an Android that has downloaded Spotify (mostly for on the go casual listening).
I got Spotify working, but it's just weird that only LDAC works which
might consume more power unnecessarily as I'm only using it for 320kbps Spotify downloads.
The other weird part is my current phone (that has my newer sim card in it but has since started to screw up) seamlessly streams to the AP80 in SBC by default, and I haven't toyed around manually selecting CODECs on it since...well...it works, although I'd avoid using it due to the screen (and one reason why I got the AP80 - so I can minimize wear on the phone until I can move and then get a new phone there instead of blowing a lot of money on one where I currently am).