PS555 vs. PS555DR

I just added a 555PS to my CDS3 and it is a large improvement. More immediacy and resolution. Not sure DR is a wise option since I have an active system, and would require 4 additional boxes DRed .

Was a PS555 a significant upgrade to your Ndac?

Given 3-4x the price relative to Ndac, I am still contemplating whether PS555 is justifiable…

Yes - it was. It’s difficult to describe the effect without using all the superlatives in the English dictionary :slight_smile:
The best way is to use an analogy - think of it as a huge turbo-charger on a car’s engine, with all the uplift in performance and no turbo-lag :slight_smile:

As to a cost - I bought my 555PS as a pre-loved one from a very reputable UK dealer and had it serviced at Class A. All for around 60% of a price of a new XPS DR. So it was a good value for money.

Thanks a lot Adam,

The hum sound issue seems to be pretty common. Does yours have it? Some say a power conditioner might solve the problem. Are you using any?

I am trying to do all the possible due D research before spending US$4k on this 555PS.

Thanks a lot in advance.

I traded an XPS for a 555PSDR to power my DAC, and was very pleased, as was Adam. I will not comment on cost, but the bigger supply brought out more music, more dynamics, with quieter background. All of this, using only one Burndy out of the PS. I realized more from this investment a few years later, when I traded the DAC for a used NDS - using both Burndy’s from the 555PSDR.


Thanks Adam,

The hum sound issue seems to be pretty common. Does yours have it? Can other 555PS owners here share your experience on that? Some say a power conditioner might solve the problem. Are you using any?

I am trying to do all the possible due D research before spending US$4k on this 555PS.

Thanks a lot in advance.

When comparing a new 555DR against my several years run-in non-DR 555 PS I preferred the latter. The DR was detailed but lacked warmth in upper-mid and HF lacked fine detail…but that was new.

After a few weeks it opened-out and improved - but to my hearing it took a good six to nine months to fully-eclipse in every way my old non-DR 555PS, so I prefer the DR version - it is vastly better in terms of detail and lower coloration and lower noise.


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Thanks Charlie,

Can the two burndy connections be used for two separate devices simultaneously? Ndac and CDS3 for example?

Ptcm10, no the 555PS should be used to power only one device.


Thanks for that observation. I suspect that may explain the ocasional preference for non-DR over DR.


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A ‘hum issue’? It’s not common at all. And no - my 5555s don’t hum.
Using. Power conditionaer is an absolute no-go with Naim ot kills a sound.

Further - humming transformers (I guess this was your question) will not really be cured by a power conditioner.

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Hi PCTM10, yes, lots of 555PS transformer hum here too. It became really annoying. There is a thread on the old Naim Forum called “Suffering from those transformer hum blues?” which charts our journey to deal with it. We tried several expensive power conditioning devices which didn’t work.

However, an Airlink Transformers Balanced Power Supply hard wired into a dedicated radial supply for the hifi worked a treat and with no downsides that we could detect. It benefitted the supercap, NAP135s and 555PS as all were suffering from transformer hum. It cost about £550 at the time.

Note that this is for a UK installation. Electrical standards vary by country, so use a qualified electrician to guide you on how to do this.

Here’s a photo of our 5kVA BPS which powers the hifi to this day:

Hope this helps, BF

Hello Bluesfan,

Thanks for the info. I wonder if this issue is only specific to UK users or global? Can any non UK PS555 users confirm that please?

I asked the potential seller. He said he doesn’t hear it, but any potential sellers would say that for obvious reason. I could be overly skeptical on this one.

I would love to try the PS555 on my Ndac/CDS3/CDX2. That said, I am trying to do all the research I can on this known issue before I take real calculated risk.


It’s akin to saying that ALL Jaguars suffer from a steering wheel vibration. Just because a small sample of people that wrote a review, drove it on pot-holed B-roads… I’m sure that Jaguar know how to manafacture a car, so that it doesn’t vibrate…

I live in Poland and I can confirm that my two 555PS, my two SuperCaps DR and my HiCap do not buzz…

This is not a UK specific issue. The root cause of the humming is so called asymmetric mains, otherwise known as DC offset. In essence, it occurs when there are a lot of “dirty” power supplies in your area that inject noise back into the electrical supply, or poorly designed switch mode power supplies that draw more power from one half of the electrical waveform thereby creating a “dc offset”.

So, if you live an an area with a “clean” electrical supply, then your Naim transformer will not be affected.

If you live in an area with many poorly designed power supplies, then the same transformer will be at risk of humming. Highly efficient, toroidal transformers of the type that Naim specify make our Naim equipment perform at their best but are also vulnerable to this type of mains borne interference.

You just have to try it and see. If it’s a problem, then install a well designed “DC blocker” or a BPS as we have done. Then enjoy the music! Given that your ndac and CD player power supplies do not hum, then it is unlikely that the 555PS will either, as all are susceptible to the same mains borne interference.

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A/V Options in Chicago makes an excellent outlet that will eliminate the hum. All my powerlines and TT chord are attached and dead silent.

I bought my 555ps exdem and it used to hum a bit but when I swapped from CDX2 to ND555 it failed to power the ND, it did however run an NDS at the dealers. Off it went to Naim where they found a blown diode and regulator on the rail not used by the NDX or CDX2 but needed by the ND, it was probably blown while it was still a demo unit but remained undiscovered. Too late for a warranty claim so might as while DR it. Somehow it doesn’t hum any more and nor do any other of my DR boxes.

FWIW, my Olive xps hums but the supercap and 135 amps do not. All plugged into the same mains spur too.
As far as your DR inquirie. Imo unless your going to DR your whole kit (maybe you have already I didn’t look) I wouldn’t. What I found was some dr and some not doesn’t really sing/gel until the whole kit gets DR’d. Call it Synergy or whatever you like. It was good hifi but didn’t bring me closer to the music until the whole system was DR. Then that was a different story.

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