Non-tech needs help Harmon Kardon & BWM
 

Hi all,
Have recently bought an older BMW M3 with the navigation Harmon Kardon unit in it. It (of course) doesn't play Mp3s. Any suggestions on how I might accommodate this feature either by an internal or external approach? Also if I was to add a balanced 4 channel amplifier to the stock gear, do you have any recommendations.
Thanks for any suggestions.