I asked this question to a computer programmer and audiophile kind of guy who sells a program to make your computer turn into a better transport, so take it with a grain of salt.... But he argued that while there are still a lot of factors involved in one computer to the next (and everything else in the chain before the DAC, etc....), probably audible differences between a serious computer system and a dedicated CD transport are going to only take place with the real high end stuff costing thousands. There, they do a lot of things to manage vibrations, magnetic fields, power supplies, etc., which can add up to a serious improvement.
I tend to be skeptical of that answer, again, because I see how well audio-gd stuff manages to do things in the DAC realm that used to be considered only possible among DACs that cost many, many thousands. Now for a range of $800-3000, you can get DACs from Audio-gd, Schiit, or Chord that I suspect rival DACs that were many times that amount just a few years ago (and even now are on the market).
Anyway, I'm happy with my set-up, but it's always interesting to chat about the potential upgrades in the future... I think that vetting out the crap in the computer process is essential to getting the most out of the Amanero/Dac-19, and highly recommend jplay (100 euros) + fidelizer pro ($70) + Windows 10 (free) if anyone is crazy about audio nuances. When I force my computer into hibernate with nothing but audio playing, and the core set to prioritize only a very minimal audio interface, it is amazing what kind of timing, soundstage, and imaging I can sqeeze out of the Dac-19.