I think the issue is split between the Crown amplifier and the efficiency of the Carvin cabs. I've used both xs and xls series Crown amps, and I was always pushing them up to clipping against a 2 raging 5150 half stacks and a strong drummer even through my Megoliath... seems they're underpowered for their ratings at least in the realm of bass applications...
Here's the simplicity: if you want to keep your rack gear, put it in front of a GK 1001RB-II. Get the GK used for around $500-600. Single cab solution: Ampeg 810e. Plenty of Ampegs moving used for about $500-800. Other fine brands of 8x10s are out there, they're just usually less common to find used. Ditch the crown.
It's where I'm at right now only I use a pedal board for my preamp stuff... the headroom is the most i've ever had w/ the GK... even beats my SVT-IIpro.
I will agree with this. The GK 2001RB I currently use is TOTALLY louder than the Crown XTi1000 I was using previously. It will blow you off the stage no problem. I didn't want to say anything about the Crown amp earlier, but since someone else seems to have the same opinion as me I will mention it.

(which I could include in the comparison I guess)