wiring question

well its not really 2 amps in one. It is a four channel amp. If you run one set of RCAs then you will either lose your fading or balance. It wont really sound worse but you will lose out on alot of options. Like if your radio has different filter for the front and back you wont be able to use them.

It really depends on the outputs from your head unit; chances are it's got output to either two amps or to four speakers. To enable your balance and fade, which you'll likely find useful, you'll need to use four channels of head unit output for the Kicker. Ideally your head unit will have two pairs of rca's, which you can disconnect from stock or existing amps, then just plug and play. Unfortunately, if it's a stock unit, the amps are probably integrated into the head unit and the only outputs are powered speaker outputs. For these you'll need to connect to the Kicker using the "high level inputs," so be sure to order the harnesses. It will work, but you'll lose some quality because the signal is needlessly run through the existing amps first, and the longer the path, the greater the possibility of adding noise or distortion. Of course if the head unit has only two rca outputs, they can be "Y" 'd to attach to all four channel inputs on the Kicker. Play around with which channel powers which speaker, because you'll only have either balance or fade, not both. One other configuration possibility is that your front speakers may be run by an integrated amp in the head unit, and the rear channels could be going to another amplifier, likely mounted in the trunk. In this case, let the head unit continue to power the fronts, and replace the stock amp with the Kicker for the rear speakers; you'll still have balance and fade (and can bridge the Kicker for double power to the rear speakers or use the extra two channels bridged to power a sub in the trunk!).

Good luck, and keep updating!