Not sure this applies to yours, but I have to give kudos to my dealer for finding this because it was driving me nuts... After a particularly "bass-y" hammering of the B&O goofing around with my son, the driver's door developed a rattle that you'd hear on certain notes. Certain road textures could also set off a twang here and there. It sure sounded like a door panel rattle, but damned if I could do anything to make it better or worse. Next service, the dealer tech spent quite a while trying to diagnose it and finally ended up driving around with the door panel off. One of the window track bolts was backed off just enough that a jolt here and there would cause the track to resonate given the right conditions. Some lock-tite and tightening, and I haven't heard a peep since.