running wires help

Ok I just bought a 98 ZX2 and have installed a Pioneer cd changer under the driver seat a Kenwood 829 600 watt amp pushing 2 RF 12's with a LA 1 Farad capacitor. All of which is hooked up to a stock radio.  I have the wires from the cd changer running under center console area the turn ons for the amp, cap and cap ran on  the right side of car the Power for the amp and cap on the left and the amp, cap, and changer are all grounded to the same point, bolt on  the rear seat.   The amp doesn't have RCA hook ups so I spliced into the rear speakers and have it hooked up that way. But when the radio is on and cdchanger is playing at a really low volume the subs sort of hummmmmmmmmm and it is quite annoying any I deas how to help thanks....

i am guessing that the cd changer is hooked up via a rf modulator. if this assumption is correct then the problem is most likley caused by a ground loop in the modulator. check to see if the ground is good, and after that check to see if the wires are picking up any kind of induced current.