I'm looking into hard disc based digital myself. Having talked to a few people, had a personal reply to my query from the editor of HiFi+, which was nice of him and been to demos, this seems to be my current take on it and the people I have spoken to.
Good computer audio is very much up with very good, middling expensive CD players. I went to a demo of Olive O6 and Naim HDX at the last weekend. I think both were up there with my Leema Antilla, a good $4000 CD player. The Naim rep said as much. The Naim DAc + Uniti serve, that combination being better than the HDX, were about equal to the Naim CDS3, not the 555.
That is good enough for me, as I could'nt swing for a Naim 555, Zanden or Nagra anyway. That's my view, I am sure others will disagree