So based on the wiring diagram for the premium, you have two channels, blue and green I think, coming off the stereo, and at the amplifier, it hooks to 6 speakers. So now that I have replaced the head unit with a Kenwood media radio with four channels, how many channel amplifiers do you purchase..... 4? Then you hook the 6 speakers, minus the sub, in parallel? Any recommendation on the type of amplifier?