It's official. Used the new rig last night at the gig. Played my Mapleglo Ric with stock high gain pickups through the 'new' component amp into the Sunn Model 215 with the JBL drivers. It's a small room, so I kept the volume down, but the flexibility of the preamp allowed me to kick the lows up enough to get a really solid low end without it being too loud overall and without making it sound too thick in the low midrange. There was something in the chain that lacked just a little: it was impressively solid down to the low G, but lost a little below that. The only differences from rehearsal, where that didn't happen, were the room and the cabinet, so I'm inclined to think that it's not the bass or the amp that was lacking.
AND IT SOUNDED AWESOME! The volume was constant all the way up the neck, solid but not overpowering. The low notes made the floor vibrate. Best sounding rig I've ever played through, and I have ideas to make it even better.
