I am restoring a 79 z28 for my son. I have had the factory radio converted to a 4 channel digital pll system to preserve the factory apperance. When I hooked the system up the rear 6 x 9's are destorted. They are polk audio db691 4ohm 100w rms speakers. I hooked a set of speakers from his home stereo that say they are 6ohm and they sound fantastic with no destortion. Does anyone know a solution to my problem. Thanks