Cannot select Output Device on Mac (shows as option though)

After advice on another thread on how to enable DSD, I am now unable to select my DAC from the list of available Output Devices in sound preferences. It shows that it’s available, but deselects after I press ‘play’. No issues if I play music via iTunes however. What did I break this time??

UPDATE: When I switch my amp to USB Audio Class 1 mode, I am able to stay connected; however, when I switch to Class 2, the output device disconnects as soon as I press play. Any ideas?