So, I've been pretty successful at engineering my whole system; but this one last detail is making my head hurt. I'm probably way over thinking it, but to bi-amp my front speakers (Kicker QS components, which come with a very nice x-over) off my 4 channel Kicker ZX-650.4, which RCA leads do I run into the input signal ports? Do I y-split the Left front left RCA and then run the 2 RCAs into the "Amp1" Left and "Amp2" Left inputs on the 650.4? (then y-split the Front Right RCA and do the same thing). Or, is there a way to feed both amps (by amps im referring to the internal amps in the Kicker 4-ch) the front right/left RCAs without using a "Y" splitter? I know there is a fader button that tells the amp it's being used for stereo mode and not front/rear/left/right mode, but I don't know if that plays into the wiring at all. Thanks for any info you might be able to give!

 

How i did mine, i ran the front from the head unit to channels 1-2, then ran rear channels from head unit to channels 3/4 for mids. Observe left/rights or your fade and all will be messed up.
Since your still running passive, you should be able to run 1 set and split them. Left into both lefts, right into both rights. Your colors wont match up. Thats unless the amp you have allows you to have 4 outputs out of 1 set of rca's, which is probably your stereo mode button. Hook 1 set into channels 1/2 and see if you get output from all 4 channels. Make sure you start with your tweeter gain all the way down.