I installed an Audiobahn amp which feeds a set of Pioneer 6 1/2 (TS-A1765--180W max) in the front and a set of Pioneer 6x9 (TS-A6975--220W max) in the back. They are wire to the amp via 12 gague wire. Each channel of the amp puts out 75 W. Ever since I installed the amp I now have a hissing in the speakers. It can really be heard when there is no music playing. The hissing gets worse when the engine is started. When the engine is reved up the hissing also gets louder. What is the deal? Will a filter fix this? All of my RCA cables are jacketed. Is there too much power for the speakers? Please help.