It sounds like you may have already done this but the Audio MIDI needs to be set up to output to the correct device. When I updated Audirvana a couple of months ago I had to fiddle with the MIDI settings to get it to work.
Audirvana / Music Streamer II Help
In May I bought Audivrana and was very pleased. I was playing it through Music Streamer II to my system. I updated Audivrana sometime in June and everything stopped working. The mute light on the Music Streamer II is on and no signal comes out of it. I have tried everything I know how to do on the computer (MacBook Pro). I have changed output in settings, made sure it is unmuted, changed output in Audivrana. It says it is playing to the Music Streamer II. But the Music Streamer II says the signal is muted. Any help would be great!