I am on a MacPro 2014 running 10.11.6 and Xplane 11.01r2 demo mode. When I start up Xplane I receive the message "The Sound System could not be initialized". My sound preferences are set to Oppo HA-1 USB Audio 2.0 DAC. If I change to the internal speakers I do not get the error message, but get no sound. [There may be none, I'm just going through the first tutorial].
I have deleted the preferences and done an update via the installer. How do I get it to recognize my DAC? No problems with sound from any other programs.