As far as I know, I can direct the output to any pair of stereo channels via a USB interface. Which ones does Multiplay support?
To see the supported modes available, the developer recommends checking Production Properties > Audio Patches. That's the menu you need to use to change the output modes for Multiplay. I recommend checking the official FAQ page where it is explained exactly. Secondly, the official website of the developer has been moved to another domain. You can access the new page using the following URL: