[ctuna]

Parallel connection between the doors and floor in the base
system make it extremely sensitive to the ohm's and power rating
of any aftermarket speaker. It is not a good idea to run the parallel
connection of head unit only power with this type of aftermarket setup.

I can see where having speakers of the wrong ohm rating would mess this
up . I believe there is a inline capacitor some where that acts a high pass
filter to the doors not sure anymore.
You could try running one speaker at a time to see if that makes any difference.
(either the door or floor)


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/attach...1&d=1209780865
http://bmwcoders.com/forum/3-er-8/bm...1-e92-e93-291/
http://technicpnp.com/menuDiagrams/d...e90_92_93.html
http://www.musicarnw.com/page-2/
http://www.e90post.com/forums/attach...3&d=1169133185
http://www.e90post.com/forums/attach...1&d=1209780605
http://www.e90post.com/forums/showthread.php?t=641323
http://www.e90post.com/forums/attach...4&d=1278871872
http://www.e90post.com/forums/showthread.php?t=343673
https://www.bimmerfest.com/threads/e...n-752.1275694/

base system wiring pre/post 3/09
https://www.google.com/url?sa=t&rct=...tDpLJPcGkw_ui_
Base System Guide
http://www.e90post.com/forums/attach...5&d=1493273253