Integrated Amplifiers

Cutting edge engineering, immense power and technical results that set new standards for 'digital' amplification... from NAD? You better believe it...

 

 

I find it very odd that the M2 is the most technically advanced and subjectively successful digital amplifier yet to grace my listening room. Until recently, right now in fact, NAD was not a company likely to spring to mind for its cutting edge technical innovation. The brand saw me through my penniless student days with a host of hi-fi products that majored on simplicity, great value and a remarkable immunity to spilt beer. But the M2 is very different. It is an end-to-end digital amplifier producing over 250W per channel and offering a technical performance that evidently sets it apart at the price.

 

MAKING WAVES 

The story starts some four years ago with the creation of an innovative‘wave-form’ amp by US company, Diodes Zetex Semiconductors. Talk ensued between Zetex and NAD, culminating in a collaborative architecture development at Zetex’s UK-based R&D facility in Lancashire’s very own silicon valley. Well, Oldham actually. From CD’s 44kHz/16-bit signals through to off-server 192kHz/24-bit high-resolution audio the signal remains in the digital domain with all controls happening in DSP. Even the final analogue output to speakers is a gain by-product of the PWM switch-mode output stage rather than a conventional DAC. The M2 is not an evolution of the classic 3010, it’s a revolution in amplifier design.

Understandably the M2 has more digital inputs than analogue ones. Consider the average CD-transport, DAC, preamp and power amp set-up. Along the signal path there are an incredible number of state and voltage changes, DACs, op-amps, filters and output transformers, each adding some sort of signature and a lot of noise to the mix. Conversely, feed the M2 a PCM signal via S/PDIF or an AES/EBU output from a transport or, arguably better still, a server and the signal remains in a single state until the output. The result is spectacular technical specs and a noise floor that is seriously and unnervingly low. Play digital silence from a test CD at the M2’s max volume setting and you’ll hear nothing from the speakers – even with your ear pressed close to the tweeter. It is surreal.

The build quality, fascia display and day-to-day operation is everything we have come to expect from a £5k integrated amplifier. It is weighty, solid and high-end looking with only the unusual selection of terminals along the back to mark its unique design. It even gets quite toasty warm in use. On the analogue side there is just one pair of RCA stereo connections and one balanced XLR pair, both of which are immediately converted to PCM. 

On the digital connectivity side you get an XLR AES/EBU bus and five S/PDIF inputs, two electrical and three optical, and an
S/PDIF output of each flavour. As S/PDIF is pure-play PCM, those hoping to feed the M2 with a DSD stream from an SACD player are out of luck. 

The two sets of 4mm banana plug binding posts are gold-plated with their fashionable clear-plastic bodies offering wings to aid wrenching home onto spades or bare wire. In a world where custom install and multi-room commands a lot of the high-end business, the M2’s back panel is equipped with an RS232 control port, 12V triggers and an IR remote connection.

For party animals NAD’s soft clipping mode can be switched on from the back panel to reduce current as the amp approaches distortion. 

 

OFF THE MENU

The front is no less well-appointed with an array of buttons along the fascia for direct source select and menu access, and a large blue two-line display that can be dimmed if not turned off completely. At it’s dimmest it is unobtrusive in a darkened room, which is more than can be said for the laser-like blue power LED that draws the eye like a super-nova. The display itself shows input source, volume level and input signal sampling frequency – although the latter frustratingly disappears a second or two after source selection. 

The handset is very much old-skool NAD-dull with chunky and translucent rubberised buttons that look like they should be back-lit but aren’t. The brushed aluminium top trim does elevate it above the plastic OEM parts-bin stuff but considering Unison Research can create a remote of substance and beauty for the £1300 Unico II integrated, the NAD’s unit is far from special [see picture, p29].

More annoyingly still, the handset’s ‘Menu’ button is actually one of the controls included for other Masters Series products and pointedly refuses to allow entry to the M2’s menus. 

On the plus side, the remote volume is responsive and the gain is nicely paced (continuous speed, non accelerating) in 0.5dB steps taking about eight seconds from mute to max. This is mirrored on the main volume knob, offering a well-weighted three turns lock to lock.

Crawling over to the rack to access the menu button on the fascia is a pain. Once in the menus you can adjust for speaker impedance, input level trim on a source-by-source basis, polarity of the balanced XLR connection and upsampling rate from direct-input mode to 192kHz. The fascia buttons are suitably firm but each has its own ‘click’ noise, varying from solid and positive on the far left to alarmingly tinny and accompanied by an uninspiring metallic twang on the far right. This indicates something not particularly well secured or damped mechanically and I can’t help thinking that the same item will be vibrating in tune with some upper-mid frequencies in use.

As the overall build quality is top notch, the buttons and remote let the side down on a five grand amp. Perhaps you can take the brand out of the budget market but not completely take the budget market out of the brand?

 

SOUND OF SILENCE

Although these issues soon become a moot point, because the M2 is the most exciting integrated I have listened to by a country mile. Frighteningly dynamic, immensely detailed, astoundingly neutral and graced with a musical articulation that compares favourably with pre/power combos costing many times the asking price. Digital amplification has come of age.

The first quality you hear of the M2 is its silence. Simply getting your ears used to the lack of background hiss is quite an experience and one that will have you setting the volume way, way too high before the music starts. Shoot me now for ever writing that an amp offered ‘inky black silences’ – they were all rather grey and wishy-washy by comparison.

Suddenly the recorded noise floor becomes prevalent, all those re-mastered ’70s and ’80s CDs showing their analogue heritage as clear as day. Even with modern discs, little hiccups and artefacts of the recording process are laid bare to analyse and ropy pressings are given no quarter at all. Harsh recordings sound harsh, grainy recordings sound grainy and flat recordings sound flat. The M2 is as simple and as ruthless as that. Of course, this accuracy is not achieved by a low noise floor alone and is testament to the M2’s fabulous resolution of detail across the spectrum from its potent and expressive bass to its smoothly extended top end.  

 

LET'S RIP...

After some convoluted high-tech shenanigans (and several calls to our resident audio server guru Keith Howard) I ripped Eleanor McEvoy’s Yola stereo SACD to a NAS Drive in 96/24 and outputted it via a quality PC-sound card as electrical S/PDIF to the M2… where the signal is upscaled to 192kHz. But this digital faffery really does not seem to affect performance as the results are spectacular, presenting an absolute showcase for all the M2’s abilities.

The first keyboard notes of track one, ‘I Got You To See Me Through’, emerge dramatically from the cavernous silence offering a immediate rush of hi-fi wow-factor dynamics. By track two, ‘Isn’t It Late’, the opening drum sequence shows the M2’s bass as incredibly tight and articulate with a depth that no integrated has the right to plumb. The bottom end has an addictive combination of dryness, textural detail and sheer scale that is so very rare in audio equipment without mortgage-size price tickets. It urges you to dial in volume to really feel the transient attack, whereupon the M2 rewards such behaviour with simply more of everything. The balance, scale and dynamics simply increase linearly without a hint of tonal-change – which is quite strange if you are used to listening to analogue transistor amps. Such is the cleanliness of the high-gain performance you will almost certainly find yourself listening at much higher levels than usual.

By ‘Did I Hurt You’ the M2 brings forth its analytical talents, ruthlessly exposing the over-saturated recording of the tracks’ harder hit piano notes. I know this track intimately but I suddenly felt my warm and cuddly feeling towards
its emotional charms being diminished by an urge to shoot the recording engineer. In fact, by the time I had listened to the entire SACD I could tell that it was recorded at either two different times or even in two different studios. There are a number of subtle balance changes and differing levels of recorded hiss between tracks, something I had never noticed before despite playing this disc through probably 50 different amplifiers. Wow. No, really, wow.

 

TIME TO REFLECT

Playing the same disc through my Sony SCD1 affords direct A/B/C comparison between digital, single-ended RCA and balanced input, and the results proved interesting. Switching to either of the analogue sources immediately added a thickening in the upper bass that congested the mix, accompanied by a subtle reduction in imaging width.

This reflects on everything from the CD player’s DACs and type/length of analogue interconnect to the M2’s ADCs, and made no sense at all. This is a digital amp and the analogue inputs are pure legacy fitment, perhaps for an outboard RIAA stage. Otherwise, don’t go there, the M2 offers so much more with a digital input.

Which leaves me reflecting on the M2 as an overall product. There is no denying its stunning analytical abilities and ultra-flat balance but I do wonder if some might not prefer a more rose-tinted presentation. The very top of McEvoy’s voice has a level of natural sibilance that is quite prevalent if you hear her live, and the M2 doesn’t hold back in exposing that on her recordings. Likewise a romp through my AC/DC back catalogue on CD reveals the brightness and splashiness in every recording with merciless precision, somewhat detracting from this classic rock’s fun demeanour. Back In Black sounded great but I never found myself wanting to wind up the volume, drink Super Strength lager and stage dive off the sofa. Happens all the time usually.

Don’t get me wrong, this I not a bright or forward-sounding amp. Its lack of coloration and sheer resolution throughout the top end bring every note into stark relief – even the ones that might have been better left rolled off or swamped by other frequencies. For that reason I suspect the M2 will absolutely polarise opinion. If you are a fan of vinyl character and tube amplifier warmth then the M2 will hold all the appeal of root canal surgery. If you like your hi-fi dynamic, analytical and, above all, accurate, then start saving for an M2 as there is nothing else like it at the price.

VERDICT

The M2 is the first digital amplifier I have listened to, but the best integrated amplifier – period. A revelation in almost every audio respect, its accuracy, dynamics, instrumental separation and detail resolution set new standards at the price. Revealing epiphanal micro-detailing and recording rubbish in equal measure, it is as ruthless as it is stunning. NAD can be proud of this digital engineering triumph.

SOUND QUALITY: 88%

 

 

 

 

 

 

Originally published in the June 2010 issue