This is a weird one that just started this morning. When I turn on my headlights the interior dimmer activates and the back right speaker starts buzzing. I can get it to stop by setting the car's interior lights to the daytime setting (which is really bright). If I turn them back down the buzzing returns. When I turn the car off I hear this pop noise from the back speaker every time.

 

I've messed around with the Z1 and none of the settings seem to affect the buzzing.

 

Anyone have any idea what this might be? My only guess is some of the wiring might have come lose but I dont have time to look at it until this weekend.