Well some of those block diagrams are not quite right, but I guess it depends on the narrative associated with them.
However the USB driver and interface is powered by the SU protocol board and its associated powerlines and ground plane.
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Thank you very much for all the feedback and hello again drago 
This bass, which was so warm and full-bodied with one power supply, now feels narrower with the second 555, but also more structured and considerably faster. Is it possible that this is not only due to the reduction in load on one power supply, but also due to the separate ground for digital/analog?
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100% yes. The same experience at your System?
The ânarrativeâ was looking at why/how the ND555 uses the +12.5v supply rail present on pins M & T of Socket 1, but the NDS does not (you need to check the pin out on the back of the NDS vs the ND555). And whether by not using this supply rail places a further reduced load on the 555DR power supply, in the context of improved SQ when separate power supplies are used to provide power to Socket 1 & Socket 2 independently. As Naim have stated âless load, less noiseâ
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Well indeed, however I donât have the circuit diagram that would show the SU board decoupling.
To be fair, I have to add two things. When switching from the 300 to the 500, the position of the speakers and the listening position had to be recalculated. When adding the second 555, I underestimated this point. So I moved the speakers and listening position further into the room, giving the system more air, which it needed to sound balanced.
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SoooâŚ
Nd555 with 3.11 warming up.
First impression when compared to nds which was my Best Buy since long time and which I used with 2x 555psdr since mid of January.
Nds:
- smooth and the most relaxed listen - a bit held back
- Analogue like - round and warm
- Very much together
- Loosing some details known before
- Not very deep soundstage
- Very much naim sound
- Very much immersion
Nd555
- very powerful sounding (like a bigger nap)
- more demanding to listen
- More live like sound spectrum
- More details and deep soundstage
- Less textures in the mids - but still textures
- Slightly edges and shouty (this can be a mind trick after fw debacle)
- Nice immersion
- Bass definition to die for
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I believe that is pretty much what others have described as the difference between them earlier on. But there are also those that couldnât hear any difference. Some of them moved to DCS.
What do you mean by more demanding to listen to? That sounds rather negative to me. I want listening to music to be easy not asking for my energy and attention.
YesâŚ
Thatâs what I need to found out. There is no listening and doing something else.
Nd555 has this authority! And the grip the nds is missing, nds has this smoothness which is also addictive.
And there is some adaptation period. Remember when I first tested nds I thought it was too dark. Guess what my expression on nd555 is now 
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I can understand this. Demanding attention. If you are in a room with someone playing a grand piano, electric guitar, drums etc, it is difficult to ignore.
It is authentic, however personally I do not want this in my room, I want a very engaging simulation. One has to remember that when mixed all music is not intended to recreate as accurate a representation as possible, it is to involve and entertain the listener. Very different from a live performance.
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Wonderful description. I am still wondering if the NDS should have a 2nd PS555 non dr
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Do it!
Nds is wonderful!
But timing and prat are on nd555 side!
AhhhâŚ..I want to upgrade the speakers first but the non dr Ps 555s seem to be an increasing rarity
Dr is also fine! 2nd ps is a winner!
Yes I can understand that. Very exiting but I donât want Stuart Copeland in my living room!
That is is what you need to decide. Relaxed listening with the term âbeautifulâ - this is the nds!
Engagement and like being in a concert with transparency and detail â> nd555.
There are some songs where male and female voices are layered simultaneously. With nd555 you hear both of them. Nds could not separate
Once is for sure - no matte the outcome. Nds will stay - not selling.
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Relaxing and beautiful does it for me!
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Maybe itâs good as the 52/135 has some Olive roughness.
Mine serviced ones are in storage - also not sold.
Nds might fit like hell.
With full 500nd555 is a good partner - as is the nds as well
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Yes I can imagine the full 500 must be incredible.
The old olives, as you say have some PRaT and with Sonus Faber and NDS it is exactly what I enjoy.
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