NAD has been famed in the past for its big power amplifiers - but none have come quite as huge or as mighty as the unfortunately titled M25. Weighing in at 44kg and nearly half a metre deep, not only is this behemoth the size and weight of most Krell power amps, it is just as solidly built and just as well finished too. Thankfully the price tag is far more NAD than Krell, and at under £2,000 for 160W to all seven channels the M25 offers superb material value and power per pound.
Internal design centering on a huge Holmgren toroidal transformer, power rails made from chunky copper bus bars and seven completely discrete mono power amplifiers. The spec sheet quotes a near flat response from 3Hz to 70kHz and 118dB signal to noise ratio at full power. With 160W on tap the design is certainly going to create spectacular dynamics.
Of course this is a NAD design too - a company wont to add nitrous-like power boosts to its amplifiers. Evolving from the Power Envelope feature of many moons ago the M25 now sports Powerdrive. This circuit engages a second high-voltage rail that nearly doubles the continuous power on a short term dynamic basis. Mama!
The external design shares the material mix and cosmetics of the matching disc player and processor. The intense blue LEDs show all channels in operation and the back panel offers seven phono inputs and seven pairs of binding posts that clearly wouldn't baulk at zero-gauge cable. There is a 12V trigger to complete the Blofeld scenario and a switch to engage NADs old faithful 'soft clipping' feature.
Soft clipping ensures that if you are barking mad and/or stone deaf and want to drive the M25 to its limits, it will fall into gentle 'peak' clipping rather than full-scale distortion. Given the M25's power and current reserves, you would probably be sonically crushed and picking bits of molten speaker driver out of the sofa first. The manual should warn anyone who sees the soft clipping light on the M25 illuminate to seek urgent medical attention.
It takes about a nano-second of listening to the M25 to realise it is something special in terms of dynamic headroom, bass extension and sheer control over speaker drivers. The soundstage is immense, bursting from an inky silent background with frightening realism and tautness. It is as if every note, every sound and every effect is chiselled into the air with laser like precision.
Hooked up to a big set of floorstanders with decent bass extension, the M25 renders a subwoofer all but an optional extra, such is its low down drive and power. I would go so far to say that no amplifier yet to grace the Stevenson home cinema room has ever driven my big Tannoy Dimension TD system quite so hard nor kept them under such tight control - including the £20k power-amp setup currently in-situ.
Bass and snare drum attack is awesome, underpinning soundtracks with incredible low-frequency definition. The effects extends through the entire frequency spectrum keeping a flat-neutral balance with tight control all the way from explosive LFEs up to shrill effects like shattering glass.
Dialogue is projected superbly and the M25's rendition of vocal scale gives actors with serious presence a tangible reality in your living room. This extends to music too, turning decent recordings into a full emotional experience complete with foot tapping, duck-walking or air-guitaring depending on your genre penchant.
Switching back to my reference power amplifier set up, the NAD can suddenly seem a little boisterous and heavy-handed with more delicate material. Genteel female vocals lack a little of the sparkle and minutiae tonal inflections of the very best esoterica, and it is not totally character-less... but let's get real. The M25 is a sub £2,000 power amp and comprehensively eclipses every other multichannel power amp in its class for sheer jaw-dropping performance and pretence-free home cinema enjoyment.
For me, the M25 is the star of the Masters Series and is the most versatile, weaving its potent magic with just about any processor or source you throw at it. If you like you home entertainment big and dramatic in every conceivable sense the M25 is an absolute bargain. It both ices the cake of a Masters Series system and offers itself as a first-class upgrade to just about any AV amplifier or receiver out there. Richard Stevenson