Thank you for your response. I have looked into this as I described earlier in this thread.
As I understand it yes you can send to AirPlay 2 devices from Audirvana, however to do that you have to select those devices as the output on that Mac.
So, if the Mac is in another room you have to go to that other room, select the devices, then you will be able use Audirvana.
If the devices are not selected on the Mac then Audirvana cannot “see” them. So although, yes, you can use the remote app for Audirvana on a mobile phone to select the output, that is only the case if the outputs are available to Audirvana on the Mac and for the Airplay 2 device to be available it has to be selected as the output on the Mac.
I’ve described this three times now in this thread. If I have misunderstood this then I would love to be corrected as it would be great if this worked otherwise.