2001 bose stereo loosing power
 

I have a 2001 a6 4.2 the bose stereo seems to mute when there is any power draw in the car,brake lights, heating etc.. The base driver is still working but all the house speakers drop out,not a peep. I have read that the phone mute wire can short out. does muting for the phone drop out just the house speakers and leave the base driver on? The car does not have a phone installed. Does any one know which wire this is on the back of the head unit,if that is where it even goes. Where is the amp for the speakers? It seems that the amp is cutting out. Is there a fuse or relay for the amp. the head unit and the base driver show no signs of being affected when this happens. Thanks in advance.

Can anyone tell me if the phone mute just kills the house speakers and not the base driver?