You could disable the “Use S/PDIF when available” and while the DVD is playing, right-click on the video window and scroll down to “Audio device” and you could choose “2 Font 2 Rear” or “Stereo”.
If you did happen to install the drivers that I linked you to earlier, then by default (intentionally) the front and rear channels are swapped. Go to the “kx” console at the bottom of your system tray and then you have the option on the first tab to swap the front and rear channels, or even easier, swap the plugs on the back of your sound card for front and rear.
I hope this finally helps you out.
