sounds like someone shoulda got a Delta 1010lt($379) 8 input card.....
Ive never tried using both my Audiophile and my other card at the same time but i will try and let you know....i would think there would be some sync issues to deal with.....
I think Gidge is right; the cards have to have some way to lock together or both use the dame clock reference. Cards like the Delta series are engineered to work in groups of 2 or three Deltas in the same PC, but SB Lives are not.
S/PDIF - but i'm more concerned as to whether i'll be able to take advantage of the SB's A/D converter on its line in for my room mics (after the preamp) - i don't currently have an external converter (and unless if there's one thats cheaper than all that i've seen, it may be many moons before i do...) - what about running both MIDIs at the same time?