I vote that PG go buy 2 Tascam us800 units right now for $99 and try this out. oops, just checked and the price for the us800 is back up to $250 for now. Just a few days ago it was at $99 again at musician's friend.

There's no cheaper way to get that many outputs. I don't know that two different USB interfaces can be 'live' to the PC - it seems like you'd have to pick one or the other.

-Scott