[DaveJB]

Awesome, that's a huge help. I have a few threads going and I thought I had mentioned it. I have the Hifi System Professional, the one with the upgraded speakers.

From what you've said, I have two solid options:
1. if I can find a DSP with a convenient volume control, I can tap off the signal from the head unit. One question this opens up is that if I use the signal here I bet I can't later add the Intravee II unit? Oh, and to make sure, the signal from the head unit includes when I play the CD? I'm thinking it's possible the in dash CD player output goes straight to the amp.
2. get a DSP that has 8 analog inputs and "un-eq". Sadly the MS-8 isn't for sale anymore, though since it's not I haven't researched it that much.

What bums me out about all these DSP units is that for $250 I can get everything I want in the Pioneer DEH-80PRS but can't find these features in a DSP for less than a $1000. It has auto time alignent, auto EQ tune (automatically adjust for the car's acoustics), it has auto volume adjustment as your car speeds up, and realtime AutoEQ that compensates for sonic changes as you drive (aka, turns up the bass to help with road noise). I've been running this head unit in my Z3 and LOVE IT. You get so much for so little cost.