Hi all. This is my first post, but I've been a fan of this site for a while. My problem is with my 2002 325i with the Harmon Kardon stereo. When I bought the car, the stereo was awesome. As the car aged, though, the driver's door started to sound less crisp than the front passenger door -- most noticeably with the high-end sounds. As the problem progressed, the driver's door started sounding more muddy than the passenger door. I took it to the dealer, but trying to explain that the sound was more muddy to a BMW repairman proved to be a fruitless effort; they couldn't tell a difference.
The next stage of this problem came when the mid-bass (the bottom speaker) started distorting at high volume. The speaker was replaced, and this solved the distortion problem temporarily. The speaker started distorting again, and was again replaced. Recently, I hit a speedbump while shutting off the stereo and broke the volume knob. The dealer replaced the head unit (which is cool, as my car was produced 01/02 and before this replacement wasn't capable of Bluetooth, Sirrus, iPod, etc.) and the problem persisted. They then replaced the amp in the trunk. Still there.
Last week they had the factory rep look at it and the mid-bass was replaced again, along with the tweeter (the one up by the outside mirror that says Harmon-Kardon on it).
With everything they do, the problem is temporarily fixed, but now (four days later) it's worse than it's ever been. When you go from right to left with the balance, it sounds like a completely different stereo and the mid-bass is distorting again. My problem is, aside from the wiring harnass(es) there is nothing left to replace and the factory rep told me that very specificly.
Has anyone else had this problem? Any insight as to what could be the problem and what can fix this?