Hi @Simon-in-Suffolk et all,
Currently Apple are forcing an aac link on Airplay2 when using Apple Music, even if the ui is saying lossless. This was documented on one of their FAQ pages.
So example:
Now lets turn on the internal metrics airplay2 trace:
Observe the aac 256kbit link.
As and when Apple ‘open the taps’ then that can go to 16/44.1 alac. Beyond that will need Apple to update Airplay2 in devices. There will be complexities of switching rates, gapless, buffer sizes and clock tracking different rates.
Best regards
Steve Harris
Software Director
Naim Audio Ltd.