Nain Audio

I once had the CDS3, and then later, the CD555.  I liked both players, but, the CD555 is quite exceptional.  It had a meaty, full sound, without being murky or sluggish like other players that can be described this way.  But, because of how hard it is to access a large CD collection, I bought an NDS server (I loaned the CD555 to a friend).  I did not think the NDS sounded as good as the CD555 player.  When I upgraded the server to a 555 server/uniti Core  setup, I traded in the CD555 player.  I like the new server, it is pretty much on par with the CD player.  By the way, I utilize a single 555 DR power supply and do not plan to upgrade by getting another 555 DR power supply.

about 3 years ago I had the CDS3 w/XPS hooked into a 250, 252.  I then was able to acquire CD555 w/ 2 555DR'd PSU.  At that time I had never before seen or heard the CD555.  I bought the 555 pieces used from a dealer for around $15k, a fantastic opportunity, I believed.  I was nervous about whether the new player would be substantially better than my CDS3, which I thought was great.  When I received the new gear I hooked it up and kept the CDS3 connected as well so that I could do an A/B comparison.  

I placed a copy of Hotel California in each player and pressed play simultaneously on each.  As I listened to the CDS3, I got a bit nervous because it sounded very good.  About 30 seconds into the cut I switched to the 555.  It took no more than 3 seconds to have an OMG moment!  That's all it took to alleviate any and all concerns I had about the upgrade being worthwhile.

Now, to be fair, besides the difference in transports, the power supplies were not the same - an XPS for the CDS3 and two 555's for the CD555.  That being said, the 555 came much closer to sounding like vinyl than I thought any CD player ever could.  I have since upgraded the rest of my system to a 500 amp and 552 pre, both DR'd.  Those upgrades proved, even further, just how fantastic the 555 is.

This is a very long answer to your question, but I hope it helps.

BTW, I just arranged to upgrade from the 500/552 to a Statement.  It should arrive in about 2 or 3 weeks.  Obviously, I cannot wait to hear it!

I agree that the 555 CD player is remarkably close to vinyl in terms of sound.  When I went from that player to the NDS server, what I noticed was that there was a substantial increase in the difference between vinyl and digital playback.  I could try to adjust the tonal balance using my speaker controls, but, I am too lazy.  Besides, I don't think a change in tonal balance would have addressed most of the difference.  I feel that the 555 server is closer than the NDS to sounding like vinyl, but I do suspect that the CD player is even closer (I can't confirm this because I traded in the CD player. 

The lucky person who bought my old 555 CD player got something really nice sounding which should deliver years of pleasure (because it had a new transport recently installed).

Yeah.  I still have my CDS3 in a second system with my old 250 and 252.  I found that the NDS sounds very much like the CDS3, even when played through a 500 and 552 and two 555 PS.

Just a note, you can find Naim clones, mainly NAP200 and 250s, all over AliExpress. You can find higher end models and power supplies on Taobao.