If you have some software to send the input from one sound card to an output on another sound card, I think this could work. However I would check for latency problem within the laptop.
Furthermore, I don’t know if I would trust my laptop to be such a central part of a live show… loosing a recording is not nice at all, but loosing your amps during a live show… feel free to test this and let us know 
Wouter
My prayers have been heard, Dante is coming!
