Originally Posted by TeeSter

Assuming that the radio actually has controls for remote access of course. I'd think most of them do to have volume controls and such... but now you are asking it to recognize names of albums and what the sounds are for them... and transfer that info across..... Its easy to make it control the volume and allow you to say "track 4 disc 3" but the instant you have to tell it to access a certain mp3 via album and artist name.... its not a simle little module anymore. Presumably the MP3s are in the dash unit.... so you have to be able to trasfer that info too.

Basically the head unit has to be "ready" for it from the beginning.