usb-dac won't install as soundcard in dietpi-config

I am a new DietPi user; looking forward to using it with an Allo DigiOne Player. Unfortunately, after installing DietPi_RPi-Stretch v6.8, updating to v6.9, and installing Roon Bridge, I am unable to install usb-dac (USB Audio DAC) as the default soundcard/ audio option in dietpi-config. When I select usb-dac, the configuration reports Current: (none) and any previous audio option is deselected. Is there something I’m missing?

Ah-- I see in the v158 changelog that when setting USB-DAC, and it fails detection, the soundcard will be reset to ‘none’. I guess my next question should be what should I do to get my USB DACs recognized?