2012 Mac mini doesn’t recognize new DAC, any experience with USB to Coaxial or Toslink adapters?

I purchased a new amp with built in DAC that plays beautifully but when I plug the Mac mini 2012 that I use as a music source for my digitized music into the USB input the Mac doesn’t recognize it. It interacted fine with my other DAC. I would think it would be a simple digital to digital conversion but have any of you had any experience with a device that plugs into USB B port and exports coaxial digital or toslink optical? I would think there would be no degradation of the signal but some might work better than others. I would prefer to do that rather than send the signal to my Dragonfly or Apogee Duet DAC’s to the analog inputs and not use the beautiful DAC on the new amp. Thanks for any help.