What’s your experience regarding the 555PS DR burning in period?
Is it a matter of how many hours it has been playing or how much time it’s been switched on, or both?
Would you consider 10 days, ~240 hours playing, being enough?
I’m planning the following:
–> 2x555DR vs. 1x555DR on a ND555
I can only speak for the run in with NDS. The ND555 just took the two existing 555PS(DR) on arrival. Like the NDS, the ND555 didn’t (to my ears) seem to have much of a run in period. Maybe a couple of days to a week.
The biggest jump in performance (NDS) was the point at which the second PS went in. I wasn’t expecting much. I got a lot more. The jump was so big that I thought it had all arrived in one go, but subtle changes continued for months. From memory, I’d say about six months.
Running in a 555PS (non DR and DR) wasn’t like running in a HiCap or XPS2. The latter PSs started out tight and lean, loosening up, relaxing and stretching their reach over a few weeks, with some ups and downs along the way. For me (your experience may vary) the 555PS has always sounded composed, grippy and unmuddled from the first switch on. Subsequently, improvements have come from subtle increases in detail, space and texture.
Whereas running in a CD5 or CDX2 or HiCap or XPS2, or DAC has you admiring the presentation but waiting for the full magic, hooking up the 555PS just adds realism from the start, and the realism continues to establish itself for a few months in subtle increments. It has always been my experience that running in, bedding in, loosening up, whatever you prefer to call it, happens with the equipment switched on 24/7. Playing material continuously hasn’t seemed to make it go any quicker in my experience.
That’s nice to read 
To be honest I’m not expecting tremendous improvements by adding a second PS. I tend to be pragmatic and know that after a certain level, improvements in sound quality tend to reach an asymptote.
But I understand those improvements are greatly enjoyable, and end up being described with some hyperboles.
Your own experience leaves me with the possibility of a pleasant surprise 
I’m having a similar experience. The new 555PS DR sounds great. It’s been running for about 6-7 hours only.
There is no huge difference comparing to the “old” one (a 555PS DR I bought new in 2018).
But, still, there is a difference. It sounds perhaps a tad “narrow”, “less 3D”… those things are hard to put into words. I suppose the major changes should occur during the first few dozens of hours.
This is interesting. I thought that a long serie of charges and discharges of those huge capacitors inside the 555PS DR were needed.
I too can’t comment on the PS alone, since my ND555 was new with one PS also new and the other very recently serviced and DRd but run in.
I did keep the everything streaming and muted in the hope that would aid burn-in of everything. Whether or not it actually makes a difference, I don’t know, but it did mean that all the new Ethernet cables and everything else were also being worked fully.
But I did notice changes along the way. I may have commented on them in the long ND555 thread that has been locked but can’t remember with any precision how it all went. Certainly no more than a month, I think. It was a gradual fleshing out in detail , authority and solidity from what I can recall.
Thanks Michael!
I suppose I’ll plug both PSs after a couple of weeks.
I have to admit I’m rather curious about the outcome 
But the waiting won’t be too difficult. I’m on holidays and spend most of my time climbing (well, not today as it’s pretty stormy)
The up and down with adding a 2nd ps is lower then starting from zero and go new. So I wouldn’t have the 2nd ps separated and just start from the beginning with 2.
I just leave mine on and use it regularly - perhaps I could exercise it more but I just use it normally to run-in.
There are different phases of run-in, as I hear and experience them:
1. Initial run-in: About 10 days to clear most unpleasant effects and get it to a state where I think ‘yes-that is what I paid for’.
2. Extended run-in: About 10 weeks where things by the end of this time are noticeably smoother and more well-integrated and better detail rendition - HF extension and Bass weight and tone-color improved.
3. Very Extended run-in: About 9-10 months where there is a marked level-shift forward into a new level of performance where the music is revealed in its micro-dynamics better - there is effusively more easy detail and lower noise-floor and greater perception of dynamic range and easier flow - probably due to all the remaining low-level run-in noise and distortion artifacts falling to a very low-level.
That is how I hear it - in general - with all components both the Equipment and cables.
So you get the main settling done in 10 days for sure - except if you have a problem with install or something else not right. It should sound happy and musical after 10 days and for those with greater tolerance than me of run-in, then a bit sooner.
But extended run-in components are the real deal - get the system installed well and then just leave it alone and enjoy it and hear how it grows on you …with a periodic rebuild of Fraim every few years and cable clean (pull-out-in) every few months for low-level interconnects and every year or so for the other cables is what I tend to do.
DB.
Hi DB,
Thank you for your detailed answer.
I guess I’ll be able to wait 10 more days for an extended test, but probably no more 
As for the system setup I’m afraid it’ll have to wait a tad more. I building my own rack, as the Fraim doesn’t fit my needs. It’ll take some time before the 7 boxes find their right place into the new rack. In the meantime I’ll enjoy the system as it is.
Thanks again for your detailed reply.
Thomas
Just suggestions on what you may experience - or not! 
I think you can do similar or even better to Fraim if you observe the things it gets right - a balance of different engineering concepts to fit within a space and cost.
The main thing is not to concentrate on one thing as the killer design feature and forget all the others - they still operate even if you give them no mind.
Isolation of the set of vibrations from one box to another - energy cannot be destroyed, it will be there and all you can do is define its pathways and control resonances with careful use of damping - and prevent two or more resonances coupling (very bad).
Naim choose things that resonate in different ranges, mainly nearly above and nearly below the audio band and keep resonances from out of the mid-band - I think it works well.
Wood is used for damping and metal for rigidity - you need to control and manage resonances in the design however you conceive it.
Personally I’ve always found a lot of experiment - trial and error - and willingness to sacrifice sacred cow concepts goes a very long way to success.
If it sounds bad then it is bad is always a good place to start.
Let us all know how it goes! 
DB.
Some people have not heard worthwhile differences with two 555PS(DR) on NDS and ND555. It’s going to be room, system, ear, brain and taste dependent. It’s unfair to get someone else’s hopes/expectations up but the addition of a second PS is certainly something worth auditioning at this level. Actually, when it comes to any source component that will take an external PS, it’s worth auditioning at any level.
There were all sorts gains of the musical, textural, timbrel, dynamic, detail variety but the change was so fundamental that it was difficult, at least in the first instance, to hear past the HiFi gains. I don’t use my ears as measuring equipment. I try not to analyse what I hear. I try to sit back, enjoy the music/performance/presentation and let the technical stuff take care of itself. I’ll either like it or I won’t.
However, in this case it really was a back-to-square-one type of deal - for me. Notes started and stopped in different places. Echos and reverb went on longer and held more focus in all the things going on around them. The musical information was increased yet simplified. And on verse after song after album, double tracks resolved into four. Four tracks resolved into eight, and so on. Harmonies separated into more easily identifiable voices and the number of voices often increased. Synth bass throb resolved into multiple, discrete frequencies. And on and on.
A 555PS(DR) costs a lot of money. For the value that two of them bought to my love of music, it was a bargain.
Your mileage may vary.
Nice way of putting it Harry, always difficult for me to express the musical change it made in my system. 
So I take it you have the second PS555DR installed (your profile still states one).
I know you find it tricky to express differences but I would be interested to know your thoughts on the benefits of a second PS on the ND555, @Gazza.
Thanks i have changed my profile. Many moons ago at my dealer we added a second 555 dr to the nd555. It just made everything sound more natural, a better sense of timing seem to make the music hang together better. So with a holiday cancelled i started looking for an ex demo, rang Signals and one available…so went with it.
At home what i was not expecting was a the improvement in the bass control…which i thought was on the money anyway. The new Dylan album has a long track “ murder most foul” which he underlines some of the lyrics with very deep bass. The second psu really tightened that piece of music. It has taken the nd 555 a couple of weeks to come back on song even with an ex demo unit. Everything just sounds better, not night and day, but just sounds right.It is as somebody described the icing on an already nice cake. No going back now for me.
Wish I hadn’t asked…… 
Do yourself a favor and join the camp of 2ps, life is too short to not have some guilty pleasures…
Or save yourself some money and trade it all in and get a rossini
This morning I swapped my PS555DRs round. I now have the newer unit on the lower shelf with the older one above. I also feed digital from the upper PS, which is different to what Gary found. I didn’t know what to expect, but it’s surprisingly different. It’s only been a short while, but it’s definitely different, possibly better - only time will tell. Something to try for sure.
Being a pragmatic person and knowing that, after a certain level, improvements in sound quality often tend to reach an asymptote, I was not expecting tremendous changes. There is no such thing as magic…
And to be honest, I was not totally satisfied with the ND555… Fortunately, the recent firmware updates did really well by allowing more details and a deeper stereo image.
By adding a second PS I was expecting it to improves things a little further, but not much.
So, really, no great expectations here.
I couldn’t be more wrong… not about the magic, of course
As we use to say it the Vaud Canton (Switzerland) I am “disappointed favourably”, which means the surprise is a delight!
In the context of my system, the change is unexpected and, I dare say, astonishing!
But, how to describe it?
I’d say it’s more or less like shedding some light on a nice and well-known painting.
Colours are more vivid. Curves and forms are outlined.
Everything, of course, keeps at the exact same place but at the same time seems more separated. Every detail in the painting is sharpened, but without added contrast.
That added light makes the background of the picture more vivid, but without bringing it to the foreground.
The overall feeling is an increased depth all over the painting giving the impression that, that flower over there is behind that particular tree on the left.
Details previously hidden in the background are now very much visible.
Highs and lows are clearly improved.
Edginess or graininess I could sometimes hear is gone. Highs are now crystal clear (but no magic here, edgy recordings remain edgy).
Double-bass attacks are sharper than ever, giving me the impression of having less bass (and more bass at the same time – strange, isn’t it? This is hard to describe).
Recording venues are much more perceptible/apparent (when present in the recording) which adds some airiness to the presentation. That airiness really is THE big difference.
Microphone placements and the sound engineer’s work are much clearer (this can be disturbing with some recordings).
Another nice thing is being able to “see” the violinist moving around the microphone (this was audible previously but obvious now).
Everything is the same but very much different!
All the above description is especially true with complex music like violin or piano concertos and, of course, symphonies!
The micro dynamics increase benefit a lot to grand ensembles, but to solo instruments as well.
The piano, when well recorded, is a delight. It’s not a metamorphosis, of course. But attacks, decays and timbre are clearly much better.
You get easily tempted to listen louder!
A totally unexpected surprise is cembalo. I’m not a huge fan of the instrument. But know pretty well how it sounds. My father-in-law has one, so I hear it regularly…
On that particular recording, the cembalo sounds simply astonishing! Jaw dropping, really! It sounds almost like a real one (and this is not a hyperbole).
My wife, who usually isn’t that expansive about hifi was totally dazzled. She knows better than I do how a cembalo sounds (she had to hear/suffer it almost daily during her childhood… 
).
These are the albums I referred to for my first impressions:
As for less acoustic (more engineered and/or amplified) music like jazz, folk or rock, the difference is very much present but not as much as with well recorded classical music. Or, I wasn’t able to find a lot of well recorded/engineered albums…
The following non classical albums are nice and benefit a lot of the added PS:
Adding a second 555PS clearly takes the ND555 to another, unexpected, level.
Does it compare to sources “at up to twice the price”, as stated by HiFi Critic?
Well, this is hard to tell. I had the opportunity to audition the Soulution 760 DAC (which is twice the price) with Soulution 711 amp and Magico S3 MkII speakers (the ones I have). It’s hard to compare, both systems are brilliant. The Soulution system is incredibly airy and layered. The Naim system is very resolving and has a tremendous grip on bass!
In my opinion, the ND555 with two PS is really a different beast. I dare say it became exactly what it was supposed to be: an outstanding streamer/DAC.
So, is a second PS worth it?
Yes. Very much so! The second PS is, in my opinion, a wonderful addition.
Well Thomas thankyou. I have never been able to put words together like you to explain the musical experience i am hearing…very well done and so pleased you are enjoying the new addition😁
I am happy you like it as much. I already thought with your preferences in music you would benefit a lot of the 2nd ps. It also enables to amplify benefits in the earlier chain, NAS, Ethernet and switch…
