Ultimately it needs to be converted to analog so that it can instantiate some sort of speaker element. This can then easily be recorded with the right impedance match. This was impractical for video due to the complexity of the signal, but two simple analog signals are very easy to record and reproduce. Of course going from the analog to digital to digital compression (I will assume encryption/decryption is lossless), transmit over lossy Bluetooth and back to analog degrades the music to the point of "why bother". I listen to streaming services to shop around for songs or to play music I am really not listening to(background). Anything over Bluetooth, frankly, sounds bad for certain kinds of music.