Stereo questions...

In my wagon I have a Clarion CD player that I run deck power to 4 Polk two ways and then I run the RCA's to a Boston amp that powers a JBL 12in in an enclosure in back. It's way loud, and clean if I tune the sub tighter

I just want something that sounds decent. I plan on running two 6x9s on the rear deck and two 3.5s where the stock speaker was. I may just use the conventional speaker wires. If I could figure out how to make the fader work with just two RCA cables, that would be nice though.