http://www.e90post.com/forums/forumdisplay.php?f=27
You need to identify the Year and Model number of your car.
If you have an 09 or older e9x and its a US model you will have
one of 2 systems.
If you have the HI FI system you can put an aftermarket amp in
fairly easily and it will sound better .
If you have a Logic 7 things will be much harder as there is a proprietary
fiberoptic connection between the Head Unit and Amp .
The head unit does not identify the model of the stereo .
A Logic 7 will have a dash center speaker and graphic equalizer control
in the radio display.
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.e90post.com/forums/showthread.php?t=407085
http://www.e90post.com/forums/attach...1&d=1209780865
http://www.e90post.com/forums/attach...1&d=1209780605
If you are near Fort Lauderdale the East Coast E9x stereo expert lives there his
handle is Technic he posts a lot on the board listed above . He can fix you up
no matter which system you have.