John,
*All* processors with 5.1, whether digital or not, will work in the D-Cinema world.
OK, now for the "*".
D-Cinema sound comes in an AES-EBU Digital output. That requires a processor that has an AES-EBU input. All CP650's manufactured in the last year or so have that by default. All XD-10P or USL JSD-80D processors have it. For older CP650's and other brands, you need an AES-EBU decoder that spits out 5.1 ANALOG signal. Dolby sells their DMA8+ unit, and there are many DSP products that also perform the function. In addition, some server manufacturers (like Doremi) offer an optional 6-channel analog output card for an additional cost with the server.
So, no real worries unless you don't have 5.1 now.