Help me troubleshoot RCA problem

[MiBrowsTristan]

Alright guys, I have a 98 Explorer Limited Edition which came with the mach stereo with the amp and sub in the back. Well when I got it, the amp and sub was missing. I just hooked up an mtx 200watt amp and 2 audiobahn 12"s. I hooked my rca cables up to the black box that I fount where the amp and sub was supposed to have been. Well my problem is, With both prongs plugged into the amp, the bass cuts in and out but when its in, it sounds great and hits hard. But if I unplug one of the prongs, the bass is constant just doesn't hit very hard. Anybody have any ideas what the problem is and how to troubleshoot? I'm guessing its the black box I have it plugged into.

Thanks in advance.

 

[MiBrowsTristan]

Well I figured out my problem. The MTX amp that I got, I guess I over-estimated it. I had it bridged over and apparently, my 12"s were too much for it to handle. So I un-bridged it and it works fine.

 

[Scott2008]

try bridging the amp and running the 2 speakers in series... I bet it will hit harder and won't cut out