MQA files seem to default to 48kHz where everything else plays at 192kHz

I don’t think your Rotel is a Roon Tested device so Roon will not recognize it. Get on to Rotel to send one to Roon and they will add it. Check out this link to find out more.

https://roonlabs.com/partners

Look at this to see about setting things up for MQA. I don’t think your Rotel supports MQA but Roon should do the first unfold for you and that will give you 96/24.