Opus 21 vs. Mac Mini with Wavelength USB DAC

I currentlly own the Opus 21 and am VERY happy. I have 2,000+ CD's though. I am really thinking of getting a Mac Mini and a Wavelength USB DAC and using that as my source. What are your thoughts in terms of sound quality?

Today, I heard a Mac Mini using a ARC USB DAC compared to the ARC top of the line CDP and thought that the Mac Mini system did some things better.

Your thoughts?

Thanks,
jtwrace