Hi all, I've been trying to get FS2Open to output to my Virtual Audio Cable and I wasn't having much luck, so I had a look at the OpenAl source to figure out why it wasn't detecting my device.
After a bit of debugging I found that the launcher is to blame: the FS2Open executable checks the value of "PlaybackDevice" in the key "HKLM\Software\Volition\Freespace2\Sound" in the registry, but the launcher never creates it. Instead it creates the value "Sound\PlaybackDevice" in the key "HKLM\Software\Volition\Freespace2"! The same is true for the values "EnableEFX", "CaptureDevice" and "SampleRate".
Having created the values manually, FS2Open now correctly outputs to my VAC

I'd try to fix this in the launcher myself (and post the fix here), but the source from the SVN seems to be a bit of a mess.. so this post is the best I can do. Hope this helps!