NAP500 DR – Dual Mono Design – Dual PS as well?

Considering that the NAP500 DR is a true dual mono design with each channel having its own regulation, is it possible to use two 500PS DR instead of just one.

If so, are there any benefits?

Did someone try such a setup?



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I might be wrong but I don’t think it possible to buy a 500PS on its own, it always supplied with its 500 power amp.

Whether Naim have ever tried this it would be interesting to know.

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This has come up before. Of course it’s perfectly possible to use two supplies with a Burndy from each. The consensus was that the sound was worse. It may be something to do with the integrity of the signal earth but whatever, the conclusion was that it’s not un bonne idée.

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It would be interesting to know the cost of the 500 & 552PS actually. I suspect they will be more or less the same as the 555. I saw a price list with them separated some time back but can’t remember the prices other than I think the 500 was the most expensive.

Yes, this subject has come up before. As I remember, the conclusion was the only way to improve the 500 in a passive setup was to use two (complete) 500’s and use one channel from each. Paging @RonToolsie, he’ll know for sure.

IIRC, someone in the US tried this (pre DR if memory serves - shame the legacy Forum search function is limited). It wasn’t recommended for the reasons given above and (again IIRC) by not using a common PS, the feeds could be slightly imbalanced.

Such a shame a NAP500/PS cannot be stacked per the pic - this looks really good to me eyes.

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I think it was this topic:


Well found!

Thomas, I would recommend you read my posts on this from the earlier thread on the archive - see Ardbeg’s link, above.

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Thank you all for your replies :smiley:

It seems that adding an additional PS to the 500DR only worsens things.

I thought it could lower, even more, the 500DR’s noise floor (which is already quite low).

Adding a second 555PS DR to the ND555 is probably the only way I have left in order to improve SQ.

In Google, use such a command: dual ps nap 500

Did not work for a long time, but it seems that Google finally re-indexed the site.

Two of my DBL owning friends (at my suggestion) tried adding a 2nd 500, running only one channel of each passively. Both of them reported a very large improvement over using just a single 500 with both channels driven.
Another friend of mine went from a single 200 to a pair, again in the ‘pseudomonoblock’ configuration and was very impressed by the improvement as well.
This pseudomonoblock configuration may or may not offer VFM, depending entirely on
a) the electronics upstream
b) the speakers downstream
For instance I tried running 2x250 in a pseudomonoblock configuration with a CDX/82/Hicap/250 into passive Linn Tukans, without any perceived sonic upgrade-yet in the same system adding an IXO and driving them actively was a massive improvement. But replacing the CDX with a CDS and swapping out the 82/Hicap for a 52/Supercap showed a clear improvement using 2x250 passively.
It is not lost on me that the NAP300 shares a power transformer between two channels, yet a pair of NAP135 have individual transformers. And indeed the 135’s sounds more muscular and agile than the 300, but less sophisticated. And yes, I had 6x135s, a 300 and a 500 simultaneously chez moi. And two Exposure XVI monos too-but that is another story.


Thanks Ron, I remember from a long time ago (I think it was the Naim forum prior to the previous one) that you had been involved in these kind of experiments.

Well put re the 135s versus 300 aspect - which, I think, is what caused some (me included) to skip the 300 and get a 500 (ex-dem in my case) when costs were far more reasonable than today.

I think the underlying issue here is that while Naim’s amps are great in providing dynamics/PRaT, many speakers & systems enjoy more current/current control, and when compared to the competition (e.g. likes of Vitus - albeit a different sound), the inability to really ‘grip’ more demanding speakers is apparent, noting Naim don’t recommend bi-amping which many speaker companies enable on their kit, even at budget level.

Something like a badged 400 monoblock (likely 2 boxes!) would seem to close this gap in the range (500 to Statement) but I fear the market may be small and I’m not sure if it’s simple to design given Naim’s ethos plus, of course, yet more boxes(?). Of course, costs wise, it could end up in package terms, far too close to Statement prices.

One can dream.

Thats 12 boxes for a six pack of monoblocks, be careful what you wish for.

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I was thinking (blue sky and all that…) the monoblocks would be so good, they would replace some active set-ups, in the same way that a passive 500 (pre DR) in to DBLs was regarded by many to be superior to a 6-pack of 135s.

Having read some of the test measurement for some of the upper-range Focals (and other major manu’s), it’s apparent they need more than a 500DR to make them work as intended - and with Statement amps listed now at £170k combined £57k for the power-amp), there’s a fair bit of pricing gap to work with for mono’s to sit in with a 552DR?

Even more, it’s £180k, £57k per channel for the NAPs, and £65k for the NAC.

I ran two 500’s in mono mode back when I had the ART Emotion speakers and Neat Ultimatums. You need a special ‘y’ connector which Naim can make up for you. It was an improvement on the single 500 especially in the imaging and sound staging.

Indeed, I would say that going from 1 to 2 NAP500 in the monoblock mode is the same sort of improvements as moving from a 250 to 135s, which are essentially just 250’s with one transformer per channel (and double the heatsinking). The noise floor gets much lower and the decay and shape of notes become more meaningfull.

I’m not sure what you mean by “monoblock mode”. Unlike other high end stereo power amps, the NAP500 has no bridged mono switch. It has no monoblock mode.

Your options in this respect are one of either hacks:

  • Simply use one channel. Leaving half the 500 unused with no signal.
  • Use special leads to feed duplicate left and right signals to each power amp respectively and biamp the speakers (if they support it).

Is this what people are doing? If so, you could potentially do the same with any stereo power amplifier. Which does raise a valid set of question:

  1. Stereo biamping aside, are the gains from mono biamping (same signal fed to same amp twice driving bi-ampable speakers) going to be significantly better than other forms?
  2. Over time, does this leave you with lopsided sounding power amps as one channel will be constantly under a different load than the other?
  3. Is the improvement worth the cost outlay?