I'd suggest something like a Mojo Mac Mini with SSD, filtered DC power input, linear external PSU loaded up with 16GB RAM and Audirvana Plus hooked to a DAC that supports direct and integer mode. I've had good results with a Playback MPS-5 with USB-X and Locus Cynosure USB.
The best of the DACs
I've heard can not perform better than my CD player...most of them not nearly as well. Why would I want to open my wallet and patience to pursue digital downloads and have results not be better than what I already have. I don't mind storing the silver discs....and actually, LP's often sound better than CD's.