I totally agree about the Bass EQ. Has to be off. It would help in a sealed enclosure though, to counteract the beginning of the spl decline on the frequency response curve... I think (), another reason to build a new box.

I think I'm asking it to play too large a range. I've got my low pass at 130-ish, and my deck's high pass at 135.

 

there's no hurt in planning ahead, but sometimes you have to just tune the amp by ear and figure out what you can get away with. Try everything and pic your best result...

 

I think you should try dropping both crossovers to around the 100 hz area. I got mine sounding pretty good now at 80 hz LP, 90 HP. Unfortunately something is still rattling in my trunk despite 2 layers of Rammat and 1 of ensolite.

 

Down to ~90 on the low pass, 95 on the high pass. Much better.