That is probably even worse then. You don't have RCA's on the Sony deck? If you do, i would highly suggest that you run a set of shielded RCA's from the headunit to your amp and check to see if the noise goes away. If would definitely recommend doing it this way if at all possible. I've installed many Jensen amplfiers at Best Buy and have never had problems with noise, so it's definitely not the amplifier that is the problem. Good luck!
Cheers
rimmie
