I have a 4 channel amp, 4 door speakers and a subwoofer with 2 8" wired togather. My qustion is how do I wire the rear door speakers if I am useing the front channel for the front door speakers and the back for the sub, someone said to wire to head unit, but what wires do I use.

 

how R you planning on hooking up the subs? R you going to bridge all four outputs into the two subs. that is what I would recommend depending on your subs and power output from the amp. If your head unit is stock or already hooked up you won't even have to change them. Just hook the RCA's to the amp and the out puts to your speaker. good luck draw a design or a diagram it helps