It just has Front and rear RCAs and I'm wondering how do I get the best solution out of this. ive got some 4 inch speakers in the fron that work great 22 watt rms just like the HU, but i have some nice 6x9s in the back that im going to drive using an amp. but now how do i drive the sub? i have front and back rca out, im not using the front out because i have the speakers hooked up to the HU. so should i connect the sub amp to the front rca and connect the rear speakers to the rear rca?