Did you solve your problem? Just bought Reason with an external mixer and keyboard and I have the same problem. I did not find how to get the input from the mixer to the audio track.
-- EDIT --
Sorry, was too fast on the keyboard. Just installed Yamaha drivers for my mixer and everything is fine. It recognized Audio CODEC USB before and now it recognizes Yamaha ... USB.
Last edited by tazmatt; 2013-04-13 at 20:30.