I tried that change, no luck. I am trying to get Guillimot to give me some support on this problem. It works fine on my son's computer. he has a different sound card.
In talking to Guillimot, the only response I got was that I should reload directx (which I did) and that they will be releasing a new driver. But they had no date.
So I can't try the demo. Let me know once you get the card if you have a patch.