I have the Alpine 9857 HU and i beleive its preamp are only 2 volts:crying: I have 3 amps 2 of wich are Kicker ZX750.1s running 2 15 inch L7s. My local audio guy said a Audio Control line convertor would do my system wonders. He said it will help the bass get cleaner and louder. Is this true? Any advice is greatly appreciated.