Using Opus 21 digital input

I'm curious as to people's experience running digital signals from a computer into the Resolution Audio Opus 21.
Probably will use Mac.

Are you using a soundcard with rca from the computer, or firewire/USB interface?

I assume that my ripped cd music files can be output from the computer as 24 bit/96khz, or converted to this format at the interface before going on to the Opus 21.
How does the sound quality compare to the cd player?
First off, you have a great CD player! I really enjoyed owning a stock Opus and then later, a modified Opus before switching to an Apple Laptop and, now finally, a Mac Mini.

I used a Cal Audio CD 5-disc changer connected to the RCA S/PDIF input on the back of the Opus with great results. I couldn't tell the difference between a disc in the Cal audio and a disc in the Opus, which speaks to the proper implentation of the digital input.

If you have a Mac tower, or a Windows desktop, you can buy a sound card that has a S/PDIF RCA output, which you can connect to your Opus with a RCA terminated digital cable in order to play the hi-rez 96 kHz/24 bit files. If you have a laptop or a Mac mini for instance, you'll have to buy an external device to convert USB or F/W to a S/PDIF.

I think Steve @ Empirical Audio might be able to help you with such a device.
Thanks Sammie, that's helpful.

I just found this: Wavelength Audio's new WaveLink Asynchronous USB to coax S/PDIF converter. This might just what you're looking for....
I play streamed music though the spdif input of my Opus via a Squeezebox and it sounds outstanding - as good as the CDP in my opinion. FYI, Resolution Audio makes a "extra sources" unit that connects to the Opus that would allow a direct connection via USB if that was your preference. Perhaps ask Jeff at RA what he suggests.