[Nimbus117]

The door speakers are normally subwoofers so the fader wont work with these, it will however if you plug some rear speakers into your amplifier. You should be able to hear some noise from the door speakers - just bass though so no medium or high frequencies.

I used the head unit to power the dash and rear speakers and an Alpine amp to power the door subwoofers. You dont need to re-wire everything, I did however put in new cable from the headunit to the dash speakers. I have a Pioneer double din so ran a 3m phono lead from the headunit to the amplifier. If the headunit you are getting doesn't have phono sockets you can use a LOC (line output converter) from the speakers. It's not a big job, biggest improvement are the rear speakers.