In a way, but much more dramatic. Adding a second PS brings greater soundstage depth (more than breaddth), texture, detail and bass extension, but above all lifts the microdynamics up to the level of the CD555 and above. Well, that’'s what I found. Very impressive for piano, large symphonic works, cello solos…
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It is more than that - a lot more.
With one supply I slightly preferred the Chord Dave with upscaler in A-B demo.
With Two supplies it slaughtered the Dave and was streets ahead for me.
The Dave was more detailed and rendered acoustic perspective better than ND555 with one supply, but was a bit thin-sounding with rather dry lower-mid and not the bass resolution of the Naim.
But add two supplies to ND555 and it all came to focus and tightened-up, detail fleshed-out and there was a nice big immersive sound - it was at a far more expensive cost than the Dave/upscaler combo but it was what I wanted and it justified purchase.
That was with the original Firmware.
The Firmware update just opens the window farther and deeper into the music.
I’m finding it really surprising how much is there in music I know well I never heard before.
DB.
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Oh, I see the desire pointing on Thomas’s face…
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Thanks for the detailed answer.
I getting more and more tempted.
The thing is that 7 boxes isn’t what I planned.
If I follow that path I’ll have to rethink my lovely rack 
I clinging to the fact that the only time I’ve heard 2 ps the system lost the lovely sense of flow the music had with just one but I don’t think I want to put it to the test in my own system just yet.
Hope this is not off topic, but to answer your question about thermal stability. Gyroscopes are floated in a fluid. When the temp increases, the float tends to sink, this moves the flexleads which bring power to the motor, and that changes the torque on the float. A change in torque is a change in rate of turn read by the gyroscope. This is an error and must be controlled. I know nothing about clocks, but just know that in the Hi End, almost everything matters, so suspect that while the clock can be withing spec, in 15 minutes, it may settle for days. Gyros do that, they are within spec in minutes, but the performance improves for days, weeks, even months.
Whatever is physically going on I’ve noticed the warm-up from Firmware update has continued for a lot longer than I’m used to hearing for normal. For me with my system I hear the main obvious improvement over a day or two - day one it is good and day two it is within what I expect for great performance - then usually day three is excellent with a gradual small tail of settle over the next few days - usually.
With this update that extra ‘tail’ from day 3 has shown a greater increase in resolution - like the resolution threshold is now lower and I hear more moving into focus and resolving details - it has been doing it now for a week and that has (pleasantly) surprised me. 
I’m not claiming any understanding on the why or how aspect - interesting as that is - but it seems to happen and is audible to other people in the same way by what they tell me they hear, so a shared illusion perhaps - or more likely an effect that may not be properly explained as to the how/why, but it is there - IMO. 
DB.
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All your discussions about thermal stability raised me a question on optimal temperature in a room and weather characteristics.
I always found that my system sounds best in summer, but not very hot summer. with sunny weather and no humidity.
However recently a member posted that his system sounds best when his room was at 55% of humidity ( or outside, I don’t remember).
I tend to listen more to my turntable when it’s hot and dry outside.
Very cool, thanks! I used to be an aerospace engineer and a glider pilot, I guess I feel more comfortable with gyroscopes than with clocks. On the other hand these OCXO clocks also look quite nice … do we know which clocks are used on Naim streamers? Pink Faun offer different OCXPs, they have some information on short-term stability (which seems to be what matters in audio applications) on their web site but … the clocks are not cheap!
@frenchrooster: if you check Pink Faun and OCXO you’ll find some information on high precision oscillators in temperature-controlled chamber. They are larger than standard clocks and 10-100 times more accurate than TCXOs.
Was it really addressed to me Nbpf?
@frenchrooster: In https://community.naimaudio.com/t/nd555-firmware-update-to-3-4-0-sound-quality/6561/211?u=nbpf, you have been wandering about thermal stability and the possible impacts of the environmental temperature on hi-fi equipment.
The PF site I mentioned, has some (very rudimentary) information on OCXO clocks.
In contrast to TCXO clocks that try to compensate for temperature variability, OCXO clocks use an oven to keep the temperature of the quarz as constant as possible. They look a bulkier than standard clocks and are much more expensive. The PF SPDIF bridge, amomg others, can be upgrades with OCXO clocks. Looks like an interesting device.
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Within tolerance of that component yet… Naim often design within component tolerances which is why they get the performance they do…
The other thing is the feedback circuitry for the clock oscillator around the crystal… alas I don’t have a copy of the slides that Naim have shown me about this crucial element when I visited the factory… and this is one of the advancements in the newer streamers over the legacy models.
Because of this lead time to quiescent operation, Naim have developed advanced standby circuitry that keeps sensitive circuitry powered
I now in other areas outside of Hi-Fi digital audio I have kept precision clocks always powered as well so as to provide optimum stability and reduce sidebands (jitter). Clock oscillators are one of the more temperature finicky components I am aware of.
Having searched this thread, there’s been very little reporting by ND5 XS2 owners. I use Roon, so I don’t need update to integrate Qobuz, but am curious as to whether there will be an effect on SQ. Amp is Nait XS2. I have held off updating as I like current SQ (but it can always better — or worse).
Also, I gather that it is possible to revert to the immediately preceding firmware if you don’t like the update, but don’t know how to do this.
Thanks for any responses.
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You can’t revert firmware easily. You have to moan to Naim about it and they may or may not send you a link to the older firmware with a big caveat of support for it being an issue.
@Gromit1 When I first noticed the SQ upgrade I was posting where appropriate about it trying to confirm what I was hearing and that I wasn’t “hearing things”. I think most of the FW update questions/comments I’ve found have been consolidated to this thread.
FWIW my system is like yours (different speakers and I have a HiCapDR, Hi-Line DIN5). In the context of my “modest” system the FW update has made me re-listen to my favorite tracks/albums. In short its fantastic. My findings mirror @Thomas comments. For me it was an obvious upgrade no question about it(my ears/system). The title of this thread may have prevented NDX2/ND5XS2 users from posting here…
Thanks, very helpful.
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No problem. Early comments I found were in this thread it also has a few NDX2 users
Doesn’t appear to be an issue for anyone running a streamer from the Scottish company, as all earlier versions of firmware are accessible, allowing users to revert to the version their ears prefer. 
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Naim will obviously make their own commercial call on this - I think it will reassure their Customers contemplating an expensive product purchase.
I’m obviously fine with this version as a substantial upgrade - but perhaps in future I will be among the few wanting to roll-back and wait until another upgrade meets what I need.
Why I suggested it as a nice feature to include at some point ahead.
If I were Naim I’d be quietly working on it already. It is just managing populating a Naim App scroll-bar item menu, managed from a remote database that contains the Firmware code with a cross-ref to compatibility with what the App lists as the customer’s streamer.
DB.
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