Its been several years since I installed the rear speakers so I don't remember exactly why I did it the way I did. I know the MP66's internal amp drives the factory amp because if I turn off the internal amp I lose the front speakers. I "think" I was worried about tapping into the rear speaker outputs of the head unit to drive the rear speakers because I wasn't sure how that channel is handled by the factory amp so I used the rear RCA outs from the head unit as a easy way out. This does give me full fader and balance control for front and rear. In retrospect, I bet the factory amp doesn't use the rear speaker outputs from the MP66 speaker outputs since it wasn't designed for a rear channel so there's a good chance they can be used instead of a separate amp.

Even using a pair of 3-1/2" 2-way speakers in the back made a world of difference. Fills the whole cabin with sound.

I have a question for you. Did you paint the trim ring that surrounds the faceplate silver? I didn't but I'm tempted to do it because it would really blend the head unit into the factory panel.

Tom