Correct. And the circuits that run the regulation part of it are basically amplifiers themselves. Hence the grossly large xformer (and additional heat sink area) for a relatively modest output power level.
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Itās all in the power supply.
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From a techās point of view and being practical.
Reasons to go for a 250DR:
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Change of technology with the 009 transistors on the output stage.
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Able to drive 2-ohm loads (speakers when playing low frequencies, possibly inefficient speakers which may sound excellent. Low efficiency does not mean poor speakers, just more demanding on the amplifier output stage, current-wise) for an extended time. My speakers are 84 dB SPL, low efficiency when compared to something in the high 80ās or low 90ās. dB SPL.
Real-life example:
I knew nothing about Naim when looking for an amplifier and loved the sound when compared to another couple of amps in the showroom. My pocketbook was small at the time and I walked away with a Nait XS 2. My speaker analysis chart that came with the speakers just drops below 4 ohms at one point. Still not an issue with the XS 2, though if I had completed due diligence and some calculations I should have walked with an SN2 at the time for the ability for more headroom to make it easier on my mind. Though in reality over the last few years it has never to my ears made a difference.
Finally, if you have complex impedance speakers that are not efficient and your SN3 can not handle low-frequency loads then look at the 250DR. Otherwise, be very VERY happy with your SN3.
This forum pairs the SN3 with an NDX2 as a source.
Kind regards,
Paul.
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The NAP 250DR should be on the NAIM web site under Products/Classic series - https://www.naimaudio.com/range/marque-separates#classic-series but it is not there (although the 500DR is, when it should not be). I have told NAIM but they have not corrected their website which seems crazy to me.
I didnāt know that the 500DR has been discontinuedā¦ Or is it the Classic designation that would be wrong?
Itās under amplifiers. Bizarrely 
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It should not be in the classic section. The 500 series has its own link
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Ah - fair enough.
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Missed that. I never scroll down that far
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When I open the Naim Website and select Classic series it brings up a page with a sample of products. At the bottom there is a gray line with āSee all in rangeā and if you perform a single mouse click on that line you will see all the products.
Never noticed that line - I must be getting old and daft! I still think the website makes it difficult to find the 250 and makes it appear discontinued.
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I am a sn3 current owner and have owned a 250dr and 272ā¦ i acknowledge that the 250dr is a better amp than the the amp section in the sn3. I got the sn3 because of box count and my desire to get the ndx2 instead of the nd5 xs2. To me the sn3 allowed me to hear the very subtle differences between the two streamers and while not quite as powerful as the 272 or 282 with 250 dr nd5 xs2, for my money, it was entirely satisfying enough with my speakers. It gets me there. My combo was a little more than half the cost of the 3 separates new. I do think if my room was larger and i had full range speakers id have gone for the bigger amp for this system even with just the sn3 as preamp, and i have that option down the road! While the suggested upgrade path is the 282 preamp and use of the power section of the sn3, you could go either way. The 250 dr with a separate pre amp will simply have superior control over your speakers. I was skeptical that these separates would be more revealing, they are. That being said it is my opinion that the sn3 is the best deal in the whole naim lineup. There are some great deals in the used market for 250 dr amps, and you are not likely to lose much money at all should you decide to upgrade to a 300. Good luck in your search The listening will ultimately tell u what to do.
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just to put this into a context
I am a proud owner of the SN3
this amp just doesnāt work for me in my music room. Connecting my very high end analog mixer, to the pre amp of the SN3 is leading to too much noise humble what everā¦
Using the SN3 just for his power amp, doesnāt make any sense to me in my music room - this is why I will move him to my living room to my second system.
I am testing the NAP250DR at the moment. This one works perfect so far. no hiss, no irritations - solid like a rock.
Every listening conditions are differentā¦ thatās how it works.
thanks anyway to get more knowledge about this Power Amp
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Are those Tannoy sleakers?
Klipsch Cornwall IV
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I found the 300DR to be far superior to the 250DR which justified the further cost. I thought the 250DR lacked bass definition and wasnāt that different from the SN3 whereas the 300DR is a different proposition altogether.
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May I ask what speakers were used with the 250DR and 300dr and with which preamp, and are the amps used with the same speakers.
I have not had SN3. I went from 250 to 300DR and thought it a big jump, having previously avoided 250DR and non-DR 300 options. I have 52 and B&W 804 D3s (with Morgana and TQ Black 2).
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I auditioned the 250DR at my dealers using the same system as my own at the time.
NDX2, SN3, Dynaudio Evoke 50. I replaced the SN3 with 250DR and 282 preamp. Not overly impressed. Swapped the 250DR with 300DR and noticed a huge difference.
Iāve since gone onto ND555DR, 552DR preamp, 300DR and Kudos 707.
I think thereās a far bigger margin between the 250DR and 300DR than there was between the 250DR and the SN3. I think the SN3 is an excellent amp.
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Thanks for the response. So itās the Dynaudio Evoke 50. I do not have experience with Dynaudio speakers but read that they are rather difficult to drive with their 4 ohm impedance and lowish sensitivity. That may explain that both Supernait 3 and 282/250DR sound almost the same, and you only heard a huge difference after the NAP 300DR went in. With relatively easy to drive speakers, the outcome will likely be different.
Although I do not have experience with the NAP 300DR, my long term ownership with both NAP 200 and 250DR (owned both for a considerable period and compared them at length with different speakers) reveals that the performance is largely influenced by the type of speakers that are used. With Harbeth SHL5+, there was a big difference between the 282/200 and 282/250DR. With Dali Mentor Menuet, the difference was negligible and not worth it to me (the Dali is a small bookshelf speaker with 5" drivers and easy to drive).
Based on my experience as well as yours, this is what I think, my opinion.
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With easy to drive small bookshelves that donāt go low in the bass (6 to 8 ohm impedance and high sensitivity, cutting off at 60Hz or higher), there would be little difference between NAP200 and 250DR. Although there may be a difference in sound quality, it is small and the 250DR and 300DR are not worth it.
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With difficult to drive speakers the Nait 5, XS, SN3, 200DR and perhaps up to 250DR (in your experience) will sound unspectacular. 300 DR or above for big difference.
In summary, the message Iām trying to convey is results will vary with different systems particularly speakers.
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