Computer to DAC with no USB

I have a Benchmark DAC I purchased based on quality, not connectivity. I have been trying to figure out how to connect the DAC to my computer having only an optical, coaxial, and XLR connection at my disposal.

I found an RME audio interface with optical output (and coaxial clock), will the audio interface take output from my computer, or does it only come from external inputs?

Or am I barking up the wrong tree altogether?

Thanks