I have a 200 watt amp I am hooking up to some 6x9's. Works great with the car off but once i turn it on i get the high pitch noise that changes with my RPM's of the car. I know this is the alternator feedback. I ran my RCA and radio line to the amp on one side of my car and the power cord on the other side of my car. I have the 8 gage wires for the ground and a 10 gauge for the power. Ground cord is about 16". I've tried everything and i still get the feedback from my alternator. Is there anything else i can do?