Connecting the UR816C with RME ADI-2 DAC FS

Hi,

I have a RME ADI-2 DAC FS and need to know, if it is possible to connect both devices through optical outputs. Furthermore, will it increase the audio quality? I have a Steinberg UR44mk II Interface, but it doesn’t have any optical input or output.

I mostly use the RME ADI-2 DAC FS for listening music through headphones, but it would be nice if it could be connected to my audio interface.