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NAD M23 Stereo Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 2 0.6%
  • 2. Not terrible (postman panther)

    Votes: 11 3.4%
  • 3. Fine (happy panther)

    Votes: 100 30.9%
  • 4. Great (golfing panther)

    Votes: 211 65.1%

  • Total voters
    324

amirm

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This is a review and detailed measurements of the NAD M23 Class D stereo power amplifier. It is on kind loan from a member and costs US $3,749.
NAD M23 Stereo Amplifier Class D balanced Purifi Review.jpg

The M23 sports the nice look of other "Masters" series NAD product including substantial weight for a class D amplifier. The only miss is the touch button on top of the unit instead of the NAD logo. The touch sensitivity seems a lot better than previous NAD amplifiers though. Back panel shows the connections you expect:
NAD M23 Stereo Amplifier Class D balanced back panel Purifi Review.jpg

The M23 is based on the Purifi amplifier which we know to be a high performance amplifier. NAD has differentiated itself by designing its own switchmode power supply. Let's see if that brings something to the party.

NAD M23 Amplifier Measurements
Let's start with our usual 4 ohm dashboard using XLR input:
NAD M23 Stereo Amplifier Class D balanced XLR Measurement.png

We get slightly higher gain than reference design but that seems to have cost us a bit in noise, knocking down SINAD a couple of dBs. Strangely, we get that back partially by using RCA input:
NAD M23 Stereo Amplifier Class D balanced RCA Measurement.png

Using an average of 102 dB SINAD, the M23 breaks into our top lowest noise+distortion amplifiers ever tested:
best class D stereo amplifier review 2023.png


Noise performance is still excellent:
NAD M23 Stereo Amplifier Class D 5 watt SNR Measurement.png

NAD M23 Stereo Amplifier Class D Max Power SNR Measurement.png


Frequency response is flat and load independent which is what we want to see:
NAD M23 Stereo Amplifier Class D balanced XLR frequency response Measurement.png


Multitone test shows vanishingly low distortion:
NAD M23 Stereo Amplifier Class D balanced XLR Multitone Measurement.png


New 19+20 kHz test runs at higher amplitude than Multitone so shows higher distortion spikes:
NAD M23 Stereo Amplifier Class D balanced XLR 19 20 kHz IMD Distortion Measurement.png


Crosstalk is extremely good:
NAD M23 Stereo Amplifier Class D balanced Crosstalk XLR Measurement.png


Let's get into our power measurement and see if the custom power supply is doing us some good:
NAD M23 Stereo Amplifier Class D balanced XLR Power 4 ohm Measurement.png

NAD M23 Stereo Amplifier Class D balanced XLR Power 8 ohm Measurement.png

NAD M23 Stereo Amplifier Class D balanced XLR Max and Peak Power 4 ohm Measurement.png


We definitely have more power than the reference which is a great thing. I also like the conservative and accurate power specifications.

Transfer function gets a bit uneven at higher frequencies but calms way down by 1 KHz:
NAD M23 Stereo Amplifier Class D balanced XLR Power vs frequency vs distortion Measurement.png


The power supply seems to be juicing up the 20 Hz response.

So far our tests have been with resistive loads of 4 and 8 ohm. Let's add reactive (capacitive/inductive) load into the equation including going down to 2 ohms:
NAD M23 Stereo Amplifier Class D balanced Reactive Load Test Measurement.png


Wow, this thing is so load independent! I don't think I have tested an amplifier this good so far.

The amplifier is stable on power on:
NAD M23 Stereo Amplifier Class D Warm up Measurement.png


Pop on is likely inaudible but you might hear something when you power it down (all done with the soft on/off control):
NAD M23 Stereo Amplifier Class D balanced XLR Pop On Off Measurement.png


Couldn't figure out why the noise level was higher after I turned it off for the second time. Maybe it takes a while to drain down to nothing. It is not consequential though.

Conclusions
NAD shows how to take a standard design and make it its own with value added on enclosure, and custom power supply. The latter adds good bit more short term power to the amplifier which in my opinion is quite a bit more important than a bit of noise performance that is lost. You pay for this but remember the cost is that of the retail so margins are baked in for retailers.

I am happy to recommend the NAD M23 stereo amplifier. It is a job well done.
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As always, questions, comments, recommendations, etc. are welcome.

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Lbstyling

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Nice!

It's a hefty price tag. But I will admit the series is beautiful in person.

Of note: The 'off' pop would be audible with horn speakers like mine I would have thought.
 
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amirm

amirm

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NAD needs to learn from designers from topping. Not worth the money for that level of sinad.
It produces more power than any Topping amplifier.
 

restorer-john

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Great review @amirm.

I think we have the same classic NAD design where they are running the two amplifiers in opposite polarity, hence the excellent low frequency power results and the unusual channel separation vs freq plot.*

Note the BTL option again connects a + and a - instead of two hots in a conventional BTL setup.

1686385841108.png


*it would be illuminating if you could run the channel sep/crosstalk plot again, but invert the polarity of one output from the AP's gen, or swap a +/- on one input bal XLR. I would lay money on it becoming 'normal' looking.
 

thewas

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It produces more power than any Topping amplifier.
And it probably and hopefully will have much longer and better parts support and service, plus it won't have a newer and "better" successor every half year making it losing its re-sale value drastically.
 

VintageFlanker

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Thanks @amirm

SOTA performance for sure, at the very limits of the 1ET400A module (in fact, more powerful than reference design).

For the record, AP measurements from SoundStage:

From Audioholics:

NAD needs to learn from designers from topping. Not worth the money for that level of sinad.
They don't need to learn anything. Nor that one should buy any amplifier based on a single SINAD digit. The M23 is actually a "real" amplifier. You know, with actual power.

Edit: what @thewas just said. ;)
 

restorer-john

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And it probably and hopefully will have much longer and better parts support and service, plus it won't have a newer and "better" successor every 6 months making it losing its re-sale value drastically.

The NAD Masters series have maintained a very good resale, have proved reliable as far as I know and they've maintained the matching aesthetic for the last 20 years. I remember when I first saw the series in 2003/4 and figured, this is a game changer for NAD as long as they stick to it. They did.

But it should possess all those attributes at the price.
 

JeremyFife

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Not cheap: but measures well, plenty of power, looks amazing and is backed by NAD service and reliability... it's on my (fantasy) short list:)
Nice.
 

restorer-john

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The only miss is the touch button on top of the unit instead of the NAD logo.

I'd take the push logo proper switch over the touch too. Capacitive/piezo touch always end ups failing or getting flaky down the track.
 
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