I just had a call from my dealer who is at long last coming to install my 2nd PS on the ND555 tomorrow. After living with the 2nd PS for a few weeks there was no going back!
Should be a fun weekend! (Or not depending on run in woes)
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@Richieroo I think what you are hearing more here is the effects of switching off the system. The difference between 1 & 2 was very marked in my case. The ND555 with 2xP/S is like a definite Naim jump ie 252 to 552 for example. Once all is warmed up and running you will be very happy. The points you raised already such as the accuracy of instruments is very important to me so I valued that aspect highly. The clarity of vocals as well is wonderful. Enjoy. The bass is much more but also less at the same time! Is just very well controlled and with my NBL’s redefines what I consider accurate bass to be now! A drum sounds exactly like a drum should for instance.
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I have had my system running all day … and the one recording that jumped out at me as sounding far superior was Brother where you bound Supertramp … this album seemed to jump up a notch … the ringing harmonics from bells, pianos,sax … and the vocals were really really good…this album has a live feel to it…so I get what you say…I am looking forward to further positive devlopments
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My system hates being turned off…so i hope you get a nice uplift…stonking is not what i would expect. But the one thing that jumped out for me was bass control and then the other mid and high control came later.
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The 2nd PS is up and running - not quite what I remember, but to be expected as we’re only a few hours in. In times of travel I would have just let it run a week, but things as they are I am likely to be strapped in for the rollercoaster ride that is burn in. But already a nice uplift - particularly bass solidity and separation of instruments. Enjoying a whistle stop tour of my fave tracks and the ensuing smile. Only good things so far 
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Glad it is going well, it will get better…keep us posted.
Something strange I just spotted - the on/off button on the new PS is kind of a bronze colour? Is this a new departure for Naim?
Can you post a picture, that sounds odd?
The two-supply thing was - for me - of the character of in my Vinyl replay days, the changing of the Turntable to something better, rather than Arm or Cartridge on it…which may not help understanding my point - but I’ll continue…
The changes were a greater extraction of details, musical insight and perspective that was not of the nature of a big ‘HiFi’ thing but the sort of thing many decades ago I’d hear when getting my demo of a Linn vs Rega 2 turntable with the same Arm/Cartridge. On one level they were similar but on another it was the Linn that made everything make more sense and draw you into the performance.
My demo of two PS (on CD555 at the time) was that - a big surprise for me and the Dealer, who had no real expectation of much difference back then. When I had the ND555 demo in the Dealer shop it was first with single supply and against a Chord DAC - they both cost about the same as a combo so I wanted to hear if the ND555 was better; they were ‘different’ and the Naim was warmer and fuller but the Chord had a brighter clearer perspective - I could have lived with either.
But adding the Second supply which put the Naim combo a lot more expensive made the big difference - all warmth resolved into clean clear musical detail - the deep bass resolved into clean ‘start-stop’ notes and a lot of harmonic ‘mush’ disappeared - the mid was insightful and top-end wide and open. But that was a HiFi view on it - the more meaningful thing for me was the greater connection with music - forgetting the HiFi assessment and listening to the music - that was when I decided to go for it.
A new supply does run-in so give it a week if new at least - also sequence the mains plug-in order, which I found rather important: I have my Pre on a distribution board away from the Power Amps which are plugged-in direct to wall - plug dis-board in next to these, then plug Pre in the first clear socket (next to the mains cable feeding into the block), then the Analogue 555PS, then leave a gap or two and have the Digital 555PS farther away. I’ve posted this stuff a while back - some find it works well for them and it is easy and cheap to try.
DB.
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That power button doesn’t look right.
Did you buy the power supply new or second hand and where from?
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Brand new. Will check with dealer/naim on Monday. Agree - looks strange.
Especially amongst the line of other
power supplies, although they are all slightly different… the 552 PS on/off button is fairly matt, the other 555 shiny, and the 500 PS somewhere between the two. But this one is VERY different. Covid forcing a move to alternative suppliers maybe…? TBD… but I trust (hope?) their internal production is more consistent!!
Could be Naim have improved it - I want one too! 
…just checked and all six of mine seem the same.
DB.
Well I will say that it does actually look pretty cool. I just wish they all looked the same way!
Will get to the bottom of it next week and let you know what I find out.
Maybe a variant on the purple haze issue they had a few years ago. Or is it a golden ticket for a special tour à la Willy Wonka ? 
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I have noticed that with 2 supplies they run much cooler…before the single supply was luke warm…now they are hardly peceptively warm…
Mine have been running non stop over night now, so I’m 24hrs in just about. Really enjoying the increased transparency. I am noticing quite obvious things in old tracks that I know very well, or at least thought I did. The transparency is throwing things into light that just kind of melted into the whole previously. Like an organ that was always there in a piano led track, but I never really separated from the piano. Suddenly it’s so obvious that it cannot be ignored. Maybe due to lower noise floor? Anyway, so far so good
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The one thing that i could never get my head around with this 2 supply thing is, why should it be better?, the 555ps already has an over large transformer for what it needs, and really that is all that is different using 2 ?, yes or no.
As the 555ps is still running all the regs, yes you aren’t using them all now in each supply, but they are still being powered and so still giving off any noise etc, or is that not right?
I guess you could probably inpove things more by disconnecting the unused regs in each box ? As like i said i can’t really see what having 2 does?
Separation, well hasn’t it already got that as it uses different regs to run different bits, plus adding a second large transformer in the system, must also bring with it its own noise and other problems as well ?
Hopefully someone can shed some light on it, not that it really matters to me, but just curious really
Naim said that separating the Transformers means the measured noise is lowered further. Noise is not just from mains-in (line regulation) but also from the powered item (load regulation) the ND555. The completely separating of the digital and analogue supply current paths back to separate transformers means there is not the same cross-talk between the analogue regulator feed and the digital regulator feed.
The Regulators left unused draw almost no current and hence introduce no noise of themselves - and nothing back from the ND555.
The ND555 is not a ‘quiet’ item even though Naim will have done their best to make it so within what the engineering solution allowed - so the PS will need to have good load regulation and two supplies gives it more of that.
Naim were themselves surprised it made any significant difference as obviously they designed the 555PS to minimize such - but testing on revealing systems showed it did make a worthwhile difference in revealing systems, they measured it and found noise was lower - so it is an option! 
DB.
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And I had always assumed, when I heard the difference, that the ND555 was actually designed with 2 PS’s in mind, but happened to work well with one also. I felt that the player played so right with 2 that this must’ve been by design!