Many are not. Apple makes hardware designers jump through a lot of hoops to get to the digital signal. So most just pull off the analog. Most of the Bluetooth adapters take the analog signal, run it through an ADC, and then encode it with SBC to send through the air. It's then received converted back to PCM, and then passed back through a DAC.
_________________________
Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs
-Chris