[Riveted1]

I'm assuming (yes I know what they say!) that the Kicker box has one set of inputs and is rated at 4 ohms. I'm assuming this b/c I looked it up on the internet. Running the rear channels in stereo would make no sense. He can bridge the rear two channels on that amp (which he is already doing), run at a 4ohm bridged (2ohm st) load and have 150 watts in to the sub according to the amps ratings.

His problem is he wants more bass than that Sony amp and Kicker sub will give him. He needs better sub(s) in a proper enclosure powered by good clean quality wattage.

Another question I have for the OP is what (ball-park) frequency are you crossing the subwoofer over at? For the type subwoofer you are using, generally around 80hz give or take a bit is usually in the right area. More of my .02.....