555PS DR vs XPS DR on nDAC?

Currently enjoying an nDAC in my system.

Next move possibly is to get an external PS.

XPS DR or is there any advantage in going as far as a 555PS or even the 555PS DR.

So the question is the differences I would find between the three options?



In my experience when I was looking to upgrade PSU on my nDAC, the 555PS and 555PSDR was in a different league compared to the XPS DR. At the time I was using an XP5XS to power my nDAC and when I tried a home demo of an XPS DR I was underwhelmed. It felt only incrementally better that my XP5XS and certainly not proportionate to the price tag, so I stuck with the XP5XS. Later when I tried pre-loved 555PS, the improvement was huge and obvious within seconds. That said, I’d stick with 555PS unless you have several other DR components in the system. But if you have, the 555PS DR will show its worth.

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Well I only tried the XPS on my NDAC for a short time… it was ok but nothing special. The 555PS non DR was something else… it gave a lovely organic feel to the NDAC with good drive, dynamics and pace with great mids… superb for rock music.
I found the 555PS DR over egged the NDAC and it veered into highlighting… not nice to my ears…
The NDAC strong card is not fine treble and upper mid subtle detail / timing … and the 555PS DR seemed to show this up more… where as the non DR kept everything in proportion and natural…. all in my opinion of course.
I wrote a bit about this on the old forum.


Here in North America the 555PS non DR is very very hard to find. I’m using a XPS Dr on my nDAC and it’s lovely with my level of gear/kit. My little brain couldn’t justify a 555PS Dr that’s twice the cost of my SN3/HiCapDR.


No contest CDP555DR every time, don’t be tempted by the non DR versions, you can no longer update and difference in cost preowned is not worth the savings.

Can the nDAC be upgraded with the new NPX power supply?

What are you using to feed the ndac.

I found when feeding it from a low quality transport, an XPS made very little improvement to sound quality.

With anything else, perhaps, but I’m with Simon here, to me the non-DR 555PS is a better match with the NDAC. That’s the only time I’ve thought a non-DR power supply was preferable to the DR version.
Naim may not be prepared to update it any more, but they can still service it.


Indeed, and I wonder if a non DR but services 555PS actually has a higher value in the market now because I suspect rarer.

Unfortunately it can’t. Steve Sells from Naim confirmed this awhile ago when the New 200 series was introduced. The details are somewhere here in the forum…

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When I was running an Ndac a while back I had both the non DR’d and DR’d 555 power supplies in use. They both make a huge difference to performance and would compare the two sound signature similar to interconnect cables in that the non-DR was more like Naim Lavender cable, a bit more brash but very musical. The DR version was much more like Superluminer, darker, quieter and far more realistic tonally. I personally wouldn’t be too swayed or worried which version you use. Both will be fantastic!


Interesting I had the complete opposite experience - literally - between the DR and non DR when I had my NDAC.
Perhaps one needs to say best borrow first.
I did not particularly like the DR on the NDAC… it became too hifi, non musical and less realistic for my ears.

The NDS however was very different - that excelled with the DR 555PS and less so with the non DR … but then the NDAC was built and voiced with pre Discrete Regulator technology, where as the NDS was very optimised to work with the DR technology.

The best sounding setup I ever heard with a NDAC was 555PS non DR with the NDAC and a 555PS non DR powering an NDX feeding the NDAC. This was with a 552 (can’t remember whether it was DR or not) and NAP300. Absolutely superb… in my opinion… though perhaps not a very likely combination.


Meridian 200 transport / Orelle XTC transport both CDM4/19 mechs.
But hopefully will be trying a Jays Audio with a CDM4/19 mech in a month or so

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I don’t disagree with your findings on your system and realise that these sort of traits can be very system dependent. I was using the non-DR version with my old CDX 2.2. Funny, the CDX2 never quite gelled with the 555PS but with the NDac/555PS it was stonking! That was until I tried the CDP555 and realised I’d only been scratching the surface of what you could pull off a CD.

With all the DR stuff I now own I’d say that they all have that typical DR quality to them. One comment I will make though is that I have noticed some slight variability in performance. I recently replaced an older, DR’d but serviced supply for a supply that was just a couple of years old and I thought it was noticeably better.


I always had nDAC powered by 555PS-DR and never had the chance to compare it powered by non-DR PSU. Rest of the system was NAC 552/non-DR and NAP 300. The SQ was fine. Then I upgraded to NAP300DR and SQ got better, so I decided to upgrade also the 552 to DR and then ran into disaster. The MF and HF became very hard sounding and unpleasant. So trying to find where is the problem I replaced the DR with non-DR for the 552 and the highs became softer and more pleasant, but the bass lost some of the control. Second experiment was to run the nDAC without external PS and put back the DR to 552. Again the sound was more pleasant. I came to the conclusion that DR adds acceleration to the attack of the signal and when having it at the source, at the preamp and at the PA, the effect is adding up and becoming unpleasant. So I think Simon had his experience, because probably he had rest of the system already DRed. I need to find a non-DR 555 PS to try it with nDAC and 552DR.

Hi, yes that sounds familiar, I think at the time I experimented with the non DR and DR 555PS on my then NDAC I was using a 252 DR (ie SuperCapDR).

Which power amp were you using?

I think at the time I had a 200 and 250.2

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@Simon-in-Suffolk , which streaming service have you been using? I have been ignoring this question, but I think the problem could very well be there. So I downloaded the Gypsy Jazz Trio in pure dsd-128 and then streamed it from the server and compare it with the same albums from Tidal. The dsd 128 is just fine, even little soft, the one from Tidal is hard sounding. Both played with nDAC/555 DR. Would be interesting if you or someone else can replicate and share experience. For me the issue may very well be the streaming platform.

Digging further found interesting video in youtube from goldensound channel on the Tidal/MQA . The publisher claims, as far as I understood that MQA brings overshooting in the square wave transient and pulse functions . Further more says even the normal flac files are actually converted from MQA, i.e. they are not the original bit perfect files.