Has anyone been able to pinpoint the problem? I have the same issue with my '13 M5. I had the same issue with my '11 750i. It almost seems as if the tweeters are blown. I have taken both cars to the dealership several times and they look at me like I'm crazy. All they say is that the stereo is operating correctly. They blame the quality of the songs being played through the iPhone etc. When I tell them it does the same thing while I'm on the phone (Bluetooth) they doesn't have an answer. I guess since I lived with the issue on my 7 I'll end up doing the same with the M5.
