Actually, it will handle DVD (spdif digital out) output just fine, "but" only in two channels.
It will not have the processor/chipset needed for modern multi-channel sound.
You can however take those two (L&R) channels and run them through your preprocessor (SSP) and let it do an analog processed matrix to multi-channel and see how it sounds.
Chances are you will prefer running the DVD digital out to the SSP's digital in overall. This means you can sell the Theta to fund something new.