So far for me at least, Volumio simply doesn’t work.
Roon is very easy to configure for a variety of hardware without having to be a Linux expert.
I had Roon up and running in nothing flat, using the HDMI port as the sound output. Changing to a DAC connected via USB is about as easy as it gets.
Volumio doesn’t seem to list all the sound output options in the provided drop down, only PCH.
I’d love to actually hear what it can do, but so far, nothing. Perhaps when it is installing and detecting hardware it could actually locate the HDMI sound option since it doesn’t seem to have a problem providing video via that same HDMI connector.