I have a 2005 camry with a stock JBL systems. I had a shop install an 800.5 Precision Power Multi Channel amp, 1 channel for the woofers and 4 for the front, 2-12" Polk Momo woofers, and 6.5" Polk Audio mids and highs; they also installed 2-PAC SNI-35 adjustable output adapters. They installed the power down cables down one side and the speakers wires down the other side of my car. The problem that I’m having is when the radio is in the off position; I get an engine noise through the speakers. It's not a very loud noise, but loud enough to bother me, The second problem is when the radio on switched on, there is a slight feed back noise at very low levels. What products should I look for to correct these problems.