Okay, SO I used to have the Pioneer 8400MP deck, with 4V preamp outputs, going to an oldschool MTX 2200 Amplifier. i don't remember if it pushes out 400W max, or 350, but regardless it's a little 2 channel amp, connected to some kickers. With my old deck, (the 8400MP) it bumped great! I loved the sound and everything. But I sold that deck, and bought a brand new Premier 860MP deck, with 6.5V preamp outputs. Well, needless to say, my bass has actually gone down, and the amp has started to cut out. I added ports to the BOX of my speakers, but that should have added bass, rather than taken it away. The box was specifically made for those speakers, with required airspace, and required ports, (4" ports) but with the new stereo, the bass isn't as deep, or loud, and the amp cuts out. I added a 1/2 farad cap, and it still does nothing for my amp. is 6.5V to much for the old amp? I think it's the amp, cuz the stereo is BRAND NEW! and the amp is about 10 years old. Any suggestions?