I have an amp mounted under my passenger seat that powers the front speakers and wires going to my trunk for my subs (8 ga power, rca's, remote). I recently got a pair of used amps for my two subs (SoundStream D200 II bridged mono into dual-voice coil subs, wired in parallel). I tried each amp out individually and they worked fine, so I went ahead and screwed them to the back of the sub box and wired them up, complete with distribution blocks going to the power and ground wires. I attached the sub box into the trunk wiring with the negative battery terminal off. The leds light up on both amps, but no sound comes from the subs. Also, when the car is turned off, the sound from the front speakers is VERY quiet -- I have to turn the volume almost all the way up to even hear it. After I start the car the volume is normal from the front speakers, but still no subs.

Any ideas? The volume difference thing is most puzzling to me -- it didn't do this before I installed the sub box.