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.