most factory head units do not have pre outs for amps. you need a line out converter that takes high input from your speaker wires and turns them into a low level rca output for amps. There should not be any hum if your run your wires right. do not run rca's with your power wire on the same side of your car and you should be fine. Oh, and that head unit must have a built in amp for your inside speakers only.