Oops, it doesn't handle a digital optical input. But, I guess you COULD put a D/A converter in there if you wanted. A good-quality M-Audio D/A converter like
this that retails for $300. As another option, you could try using a standalone Mackie Onyx preamp (1U, 8 inputs) that features a plethora of digital I/O. I'm not sure if it's what you're looking for, but it might be the ticket. It's about $1000 from Musician's Friend.
It has 8 Mic inputs, 2 of which can do direct input. It also does a bunch of D/A, A/D stuff too (I think it goes both ways, but I'm not 100%). If need be, check out the Mackie site and forums, they should have all the answers you need.
Edit: Reread your posts, and I think my first suggestion may be the best bet. Check it out.