Yeah,I'm with the others who said it's highly unlikely you'll find a prepro that will not be a letdown from your CJ preamp, and any one that might will likely be on the expensive side. Sounds like 2-channel is your greater priority, so why sink $$$ into processing center/surround channels just to get decent stereo performance out of a prepro?
I'd explore a decent AVR (Onkyo/Integra, Marantz, NAD, etc.) and let that do the HT processing and power the center/rear channels (or maybe use the Threshold for the center channel) while keeping your PV5 in service for stereo listening. You could get a good AVR for under $1000 and have money left over to put into other the other things you need. As stated earlier, you just hook the front L/R outputs of the AVR to unused inputs on the CJ, set a reference volume level on the CJ (I used 12:00 because it's easy) that you set it to for home theater duty and you're done. Best of luck in whatever route you choose.