I audition it and honestly do not know what all fuss is all about. Some reviewers may like it but, appart from clean and powerfull sound it is nothing special. It sound just too 2 dimensional for my taste. In fact I do not like Naim sound at all.
I have to disagree with you. To my ears, CD555 doesn't sound like a typical Naim at all !
Simply put, the $32k Naim CD555 is the best RBCD player I have tried so far. However, the difference between the 555, and Accuphase DP-78 in RBCD mode (which is another excellent player, BTW) although noticable, was not huge by any means. I was expecting to be (literally) blown away, but what I got instead was a bit better bass, better PRAT, slightly wider soundstage with better defined outer edges. Nothing really major.
I have to say though, that the player is VERY complete sounding. With all other players, there were things that I did like and which I could identify almost instantly (Accuphase may be a bit too smooth and safe sounding at times, EMM has problems with bass and PRAT), things that in a long term may eventually lead to the lack musical satisfaction. The 555 was different. It doesn't have the obvius "flaws" or sonic traits. It is just ... complete.
Having said that, I have problems with persuading myself that the player is actually worth that much of money. The price premium over the Accuphase DP-78 (which costs ~ 1/3 of 555) is hard to justify, unless you are you have money to burn or are looking for the best of the best, irrespective of cost.
It is also worth mentioning, that I have not have a chance to try some of the very best players discussed in this thread (Esoteric and AA stuff), so my comments are based on my expirience with EMM Labs DCC2 se / CDSD se and Accuphase DP-78.