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NAD’s new M66 streaming pre-amplifier back story goes like this… 

It’s the product of a 50+ year reputation built on solid performance, value for money and innovation, combined with a streaming and multiroom software system (catering for up to 24bit/192kHz resolution) that ranks among the best both for ease of use and for intuitiveness.

NAD introduced its Masters Series 10 years ago - all top-of-the-range kit with audiophile-grade componentry and a gutsy, confident design that made the traditional black box look distinctly old hat. Four years ago, the crowning glory of the range was announced: the M33 integrated amplifier with its cutting-edge ‘Purifi Eigentakt’ hybrid digital amp technology. The result was virtually distortion-free sound, whatever the volume level. That same amp technology then appeared two years later in the ballsy M23 power amp. But where was the partnering pre-amp? 

Announced a year ago, the M66 is finally here - and it has the same credentials in its classy, unpretentious looks, awesome technology and unadulterated, distortion-free performance. 

In essence, the M66 pre-amp is both a digital amp and an analogue amp with separate signal paths for analogue and digital sources and separate power supplies for each. They’re heavily screened from each other to prevent sound-degrading signals and cross-talk interference.

If you are an analogue-only sort of person, using a turntable with the MM/MC phono stage for example, the M66 has a selectable ‘Analogue Direct Mode’ that bypasses all digital processing. For this review, though, I stay in the digital domain and use both CD and the BluOS system to access my NAS library (as well as the considerable selection of music streaming services available within the BluOS app). 

At the heart of the digital section is an audiophile-grade ESS Technology Sabre ES9038PRO DAC. This is a design known for its wide dynamic range, ultra-low noise and distortion, and impeccable time-domain performance. NAD says it is a considerable step up from the DAC in the integrated M33, and several other components in the digital signal path are similarly improved - the results certainly bear testament to its quality.

The M66’s back panel has an array of inputs and outputs, and besides the usual suspects there’s HDMI eARC (for use with aTV) and USB-A. XLR balanced and RCA unbalanced outputs are both provided for connection to the power amp (I used balanced for this review), plus four (yes, four!)  outputs for subwoofers. NAD’s rationale for this inclusion is that by adding carefully placed subwoofers in a listening room, bass can be better focused and - perhaps counter-intuitively - tighter. Adding more bass to get less, in other words - NAD swears it works… 

NAD is one of a few audio companies that properly takes future-proofing into consideration - so the rear panel also features two expansion slots for use with the latest iteration of NAD’s ‘Modular Design Construction’ technology. They offer the potential to add new, as-yet unimagined features by inserting an MDC2 module into one of the slots.

To the front end. With just a discrete on/off touch switch sitting on the top surface and set flush within the brushed alloy frame, the front panel is minimalist in the extreme. There’s a large colour touch-screen and a volume control - and that’s more or less your lot.

The silky-smooth volume control isn’t the conventional potentiometer you’ll find on many other amps, but rather a series of tiny resistors that provide (according to NAD) a cleaner signal. In practice, you can turn it up to 99 percent without a hint of degradation or distortion in output -  although given the 2x200 watt power-rating of the connected M23, you are highly unlikely to require anything close to that sort of output. In my space, the volume is set to around 55 – 70 per cent (-24 to -34 db) and that’s ample.

At the bottom left of the fascia there’s a standard 6.3mm headphone output - rather than just an add-on, it leads to a dedicated headphone amplifier that is extremely revealing and consequently pleasing.

The menus within the M66 control app allow for a good degree of tinkering, much of it with the aim of cleaning up the signal and therefore delivering a theoretically purer sound - stuff like switching off Wi-Fi and Bluetooth to prevent any interference, switching to an analogue-only signal path (as already mentioned) and switching on the ‘Dynamic Digital Headroom’ (DDH) filter. This lowers the signal by 3db, creating headroom to allow the music to sound more natural. 

Sound quality

Of course, the M66 can be used with any power amp - but it makes sense to test it with the matching NAD M23 power amp. They were, after all, made for each other - and there is little that can be achieved with a pre-amp alone (with the exception of listening to headphones). So let’s start there. 

Purists can be a bit sniffy about the provision for headphones on a pre-amp, but the M66 proves them wrong. There’s plenty of depth, clarity and excellent imaging and resolution, and an all-round better performance than I’ve experienced with the M33 integrated amp. 

But it’s when performing its role as a pre-amp and feeding into the NAD M23 power amp that the system really starts to sing - especially when driving the wonderful Bowers & Wilkins 805 D4 loudspeakers. Whether music is streamed, or comes via CD or NAS digital library, the results are involving and captivating. Beautifully clear renditions express deep musical involvement, be it with a sharply delivered crack or with gentle seductiveness (depending on the mood of the music). And the depth of the low end delivered by the combo is truly extraordinary - some tracks I thought I knew well turn out to contain bass information I never knew existed. Never out of place, never artificially rendered, but simply doing what it should do by adding another dimension to listening.

The DDH technology is interesting inasmuch as you can hear a clear effect on some tracks yet discern very little difference on others. It really is dependent on the recording. 

Listening to the explosive Poem of Chinese Drum, and the MQA-treated cover of Take Me to the River by Talking Heads on TIDAL, there is a distinctly clearer, cleaner and, yes, more natural effect with the DDH dialled in - it just feels that there is more going on in the tracks. On others (Maps by Yeah Yeah Yeahs, Berliner Philamonica delivering Beethoven’s Piano Concerto No 5), I don’t detect any advantage in using the DDH.

With less high-resolution tracks, the M66 does a sterling job of dragging out what musicality it possibly can from a ropey recording - and I have some challenging recordings in my collection. For instance, the M66 does a remarkable job on the very rough Maulatu Astatke and Abel Aziz el Mubarek recordings from the 70s, turning the tracks into something extremely engaging rather than having you groping for the remote’s ‘off’ switch.

Living with

I have previous with the M66’s integrated predecessor, the M33. I’ve had one for a couple of years, and love everything about it – operation, output, quality, distinctive design. 

However - and this is the hard part - I have to admit that the M66 and partnering M23 power amp represents more than a hop, step and jump up in performance. And that’s even before I investigate the much-trumpeted abilities with four subwoofers to further focus the lower frequencies. It has been a pleasure having the NAD pre/power as company - the performance is formidable… But there’s a ‘but’... 

Try as I might, and even with the help of an expert from NAD, I cannot not get the Dirac room correction software to help me take full advantage of the performance. This may be because I have an early sample (both software and firmware updates are coming) - but a MacBook Pro, Dirac Live and NAD-supplied microphone to record the set-up result is not a happy combination.

For me, the bass is deep and focused, and it reaches plenty far enough in my listening room. I’m sure the added subwoofers will improve this further, but let’s keep that for another time.

One thing the M66 has in oodles is presence. It really is a very classy-looking bit of kit. The large colour touch-screen can be brightened or dimmed to your taste, and it does most of the things you would need (such as setting up presets for your favourite channels of music). What you can’t do, though, is browse music libraries using the touch-screen - you do it via your phone, though, so for me it isn’t an issue.

Countless words have been written about the BluOS operating system, so I will add nothing new - except to say that if the rest of the audio world was as simple to use, as intuitive and produced such classy listening results, the hi-fi sphere would be a much more contented space.


The term ‘all-rounder’ can have the spectre of compromise hanging over it - but that certainly isn’t the case with the M66. This is a superbly engineered item, both internally and externally. A NAD product specialist told me “we set out to make this as good as we possibly could” and the company certainly seems to have succeeded.

I feel that I’ve only scratched the surface of its capabilities - the focus on the low end is worthy of further investigation (but a bit pointless without having the Dirac room-correction software and Dirac Bass Control running to fine-tune performance for the room space), although even when running naked (so to speak), the M66 sounds absolutely captivating.

Listening notes

Beyonce Ya Ya

If you want a smile on your face, you can pick pretty much any track from Cowboy Carter and be rewarded. Tackling stereotyped C&W, Beyonce lets rip with her wonderful vocal range and some crazy backing instrumentation - even venturing into Beach Boys’ Good Vibrations territory. Chaotic and great fun, all while making a point.

Mulatu Astatke Yegelle Tezeta (My Own Memory) 

As far as ropey recordings go, this is a benchmark - yet the music is infectious and rhythmic, and the M66 does a great job of bringing the instrumentation to the fore, sorting it in some semblance of order, and capturing the atmosphere of Ethiopian jazz from 50 years ago.

Hok Man Yim Poem of Chinese Drum

If you are looking for vocal prowess, don’t come here - but if you want to experience an incredible dynamic range and some explosive effects, the master percussionist beats and rattles his way through a wide range of instruments in this gem.

What the press say

Why you should buy it

The NAD M66 is a formidable pre-amp that turns out exceptional results with consummate ease, features a design that will sit comfortably in any environment, and has enough future-proofing to be an ideal audio companion for years to come. Partner it with the matching NAD M23 power amp for sublime presentation of all genres of music.

Video review

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