hello. I have a 2002 volvo s80 with an adapter hooked up to the rear speakers to produce my rca's for my amp. Now heres the problem. When my amp is powered on and my radio is off (therefore no signal is running to my amp) all of the sudden my sub will start pounding just getting louder and louder....has anyone heard of this??? is it my wiring? ive always installed my system without any problems ive double checked everything....any ideas i can use all the help i can get!!!! Thanks so much!!!!