Correct me if I'm wrong but I think a number of new(er) cars and 3rd party head units support digital audio over USB. I know this works because I have an Alpine CDE-HD148BT which has a USB port on the back and I just plugged my iPhone5s into it last night and I was able to play music. Not using a CCK or other fancy cables. Just using the standard lighting to USB cable that comes with the phone. Funny thing is, the track info (Artist, album, song, etc.) was also being passed over the same connection and the play/pause/fwd/back buttons on the head unit could also control the music app on the iphone.
What audio protocol is this? Does USB audio support transport controls? Or is this perhaps some Apple licensed protocol?
Without a CCK the iPhone isn't a USB host either and I'm not sure if that direction of audio data transfer is supported by USB audio spec.
Edited by shaocaholica - 11/11/13 at 10:26am