are there any MPEG Hardware capture cards which allow use of your separate sound card instead of only using the on board stereo inputs ?

I have sound card with optical audio in / out and would like to use that to capture from my Sky+ (UK) sat receiver / HDD recorder (which has S-vid out and optical audio out ) as some of our movie channels are now putting out in DD 5.1 and I'd like to capture that from the optical audio.

What I've seen so far with some cards, they either don't support it or it' a bit vague in the dscription...

Seems like a logical thing to want to do so I'd be surprised if no hardware allows this.

Have read about Dazzle, Snazzi, Vitec & Vidac products.
Vidac Tech Supp. told me that their Vmagic won't do it.

THX / Steve