Additionally, when I change the USB output (there are a choice of 2 on the Innuos Zenith Mk2) the Mscaler will appear and will be active - BUT, when I try to play music I get a message “Failed to open audio device”. Then, after a couple of minutes the “Device NOT Found” appears again.
I have rebooted ALL systems several times and tried multiple USB chords as well
AFAIK this is still experimental. If you want to use Squeezelite, you should disable the DAC in Roon (click the cogwheels and choose Disable). Then got to Settings|Setup and set Enable Squeezbox Support to Yes. Return to Settings|Audio and enable the Squeezelite player there.