Link, comment seems right for this use.

It does NOT seem to support ARC which has proven problematic at times so good to see it not try that.

It supports a lot of digital audio formats up to 5.1 (check.) But then 7.1 is mentioned later in the manual at

As I read about pages 17 to 20 something I can see that using the HDMI passthrough then the audio from the HDTV optical might not be supported. I can't tell but I'd have to read it a few more times.