Don't even think of replacing Zapco with RF amps. Not in the same class. As for RE vs JL, you'll just have to listen to them in person and go with the one that sounds best to your ears. They're both great subs. If you're not into surround sound, then you don't need high end speakers in the rear. All it needs is mid bass. It would be a shame to use C2K 6 to power the subs. That amp is great for mids and highs. You'll notice the quality much more there than low bass. C2K 6 has the best amp spec in that series. Best possible configuration is to use C2K 6 for the fronts, another C2K 6 to power the rears and the sub using Tri-mode.