I will assume you will only want to use DCX2496 on the 3 front channels.
3 x Yamaha P2500S amplifiers (1 for main L and R, one for rear surrounds, 1 for center) 250 watts, 20hz-20,000Hz, for each channel, 8 Ohms. Or 310 per channel, 4 Ohms. This will let you power virtually ANYTHING with ease. Dynamic passages in music/movies is no challenge. You can go with Yamaha P3500S if you want to up that to 350 watts at 8 Ohms and 450 at 4 Ohms. A little overkill never hurt anyone...
1 x Behringer DCX2496
1x Serial cable, 25 foot, to connect DCX2496 to your PC for easy setup (or you can do set up front of DCX panel; much harder to do)
1x USB to Serial adapter (to use laptop PC with serial cable)
3 x RCA to XLR adapters (connect reciever/pre RCA outs to XLR DCX inputs)
1x RCA stereo standard patch cables (connect rear surround RCA outs to Samson S convert box)
5 x mono XLR standard patch cables (connect 3 XLR outputs from DCX to C, L and R amp inputs, and 2 for connecting S-Convert box XLR outs to rear surround P2500S amp)
1 x Samson S-Convert (converts RCA output, consumer voltage, to balanced XLR pro voltage to feed rear surround P2500s amp)
1x Harrison Lab RCA -12dB in line attenuator (to reduce XLR pro voltage from DCX output to feed your subwoofer's RCA input) ; or you can use a 2nd Samson S-Convert to feed the sub if you prefer.
1x XLR to RCA adapter to feed sub out from DCX to your RCA input on sub.
I'll have to specify sex of the XLR adapters later, if you are serious about this setup; I keep forgetting off hand, which is for in and for out...
-Chris