Pre/power amplifiers

In audio terms, pre-power amp combinations have always been the purists’ choice, since you keep the power circuits pure and separate from all the switching and knobbage of the preamp. So if you still think of NAD as a midrange purveyor of traditional separates, you might be surprised to see this pair — $6999 and $5499 respectively — taking out our first pre-power award. We saw the more traditional style of NAD component in our CD awards on p25, but in recent years the company has developed a higher-end line of amplification, based on what it calls ‘Direct Digital’ and in sheer power terms its ‘Power Drive’, a development of the company’s Power Envelope circuit from the ’80s and ’90s . This adds a second high-voltage rail to the well regulated high-current power supply to deliver ‘overdrive’ that can nearly double the continuous power on a short-term dynamic power basis. This, together with the latest nCore amplifier technology (licensed from Hypex) allows control and reserves of power that proved completely beyond reproach — at least 250W per channel, both channels driven, into eight ohms across the full audible bandwidth with no more than 0.005% THD. The M22 delivered exceptional authority and wonderfully tight, controlled bass down to the bottom reaches of even our largest and most difficult speakers.

Meanwhile the preamp (NAD calls the M12 a ‘Digital Preamp DAC’) is a modular unit, which we reviewed with three bays populated. Further modules include one with HDMI inputs and outputs, and another called BluOS, which makes the M12 compatible with the Bluesound multiroom music system from NAD’s parent company Lenbrook.

But as delivered, the three pre-installed input modules could be loosely termed analogue, digital and USB. The analogue module has a moving-magnet level phono input, a line-level input using RCA sockets, and a stereo XLR analogue audio input. The digital module has two optical digital audio inputs, two coaxial digital audio inputs, and one balanced AES/EBU. The USB module has a USB-Type A socket for plugging in flash memory or a hard-disk drive, and also a USB type B socket for plugging into a computer. In the latter mode it acts as a USB Class 2.0 audio device, so you can use it as a computer audio system that can make many other computer audio systems look alarmingly like mere playthings.

We loved both the all-out performance of this pair, and the way its ‘Direct Digital’ amplification seems entirely transparent and ‘undigital’. We gather it uses a 35-bit data path and DSP processing within a 62-bit space — so that when finally delivered at 24 bits of resolution, all rounding errors and such are several orders of magnitude below the level at which they could result in even a single sample misplaced by a single bit. Digital cunning, huge musical sound — it’s a new frontier for amplification. More info: www.qualifi.com.au