I've got an '03 E46 M3 with the Harmon Kardon stereo option. I'm considering replacing it for a couple reasons:

1) The stock CD player sucks and skips a lot.
2) Too much vibration in the doors when I turn it up (maybe an aftermarket system with more matting in the doors will help).
3) I want something that will kick some SICK bass, but still maintain the high and mid range sounds.

I don't want mobile video or anything, just a good CD player/speaker setup.

Alpine? Blaupunkt? Kenwood? Pioneer? Others?

Any help or suggestions is appreciated!
Jason