You need to find out for sure what you got.
L7 or Hi Fi if you have a car 09 or older.
Find a free vin checker site and print out your options.
look at the option number for the sound system.
677 = l7= Top Hi Fi , 676=Hi Fi
These systems can be in a Nav/idrive or in the Pro Radio versions
they are separate amp and speaker systems.
Read the following
links
BMW stereo types
http://www.e90post.com/forums/showthread.php?t=352586
http://www.e90post.com/forums/attach...2&d=1266451970
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.e90post.com/forums/showthread.php?t=343673
http://www.e90post.com/forums/showthread.php?t=138949
http://www.e90post.com/forums/attach...1&d=1209780605
http://www.e90post.com/forums/showthread.php?t=641323
http://bmwcoders.com/forum/3-er-8/bm...1-e92-e93-291/
http://www.e90post.com/forums/attach...1&d=1209780865
http://www.bawarec.ru/manuals/3er/e9...3er-e90-12.pdf
http://www.musicarnw.com/page-2/
http://www.e90post.com/forums/attach...4&d=1278871872
If you have logic 7 sound and you want to change the Head Unit
then the amplifier must go to. Why because there is and optical
connection between the head unit and amp and nobody makes
a aftermarket head unit that has the same type of optical output.