I plugged my mp3 player into the aux port (on my 2008.5 ms3 gt) and it played fine, but the manual says you can't charge it using the spare 12v at the same time as playing. Why is that? I tried doing it and the car's audio system refused to play.
First I've heard that it wouldn't play while charging. In previous y/m's if you charged while listening through the ACI you would get horrible alternator whine unless you added a ground loop isolator. What if you charge something else while listening to it? What if you charge the ipod through the lighter plug?