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"Laser-like Perfection" in a Multichannel Amp
Power is a critical component to sound quality. The demand placed on amplifiers by today's elaborate home theater systems requires additional headroom so that they reproduce clean sound free from the distortion of a taxed amplifier.
"It takes about a nano-second of listening to the M25 to realize it is quite something special in terms of dynamic headroom, bass extension and sheer control over speaker drivers," marvels Richard Stevenson in England's Home Cinema Choice magazine.
According to Stevenson, "The soundstage is absolutely immense, bursting from an inky silent background with frightening realism and tautness. It is as if every note, every sound and every effect is not simply hurled from the speakers but chiselled into the air with laser like precision."
Best Components for the Money
"They're the best-sounding components that I know of for the money, that's for sure," reports Steve Guttenberg on the NAD Master' Series in the January, 2007 issue of Home Theater magazine.
At 160-watts per channel the NAD Masters Series M25 is one of the most powerful amplifiers built today. It easily delivers lifelike sound levels even in large home theatre rooms It's also one of the cleanest amplifiers with a rated distortion of 0.03 percent (All channels driven simultaneously, from 20Hz to 20kHz.) The M25 easily exceeds THX's most stringent certification level, Ultra 2.
But it's not just the quantity of power that is important, it is also the quality of power that determines whether you can hear just a fiddle sound, or the unique character of a Stradivarius violin.
Unlike most receivers and amplifiers, the M25 can deliver its full-rated power, free from distortion for hours on end. Custom designed heat sinks and temperature regulated, variable speed cooling fans work to keep the M25 running cool under the most severe operating conditions.
Highly Sophisticated Circuitry
The M25 is comprised of seven individual 'monoblock' amplifier channels. Each channel uses a balanced junction FET input stage, resulting in exceptionally low levels of noise and distortion. NAD employs a unique electronic ground isolation circuit to prevent ground loop noise in the system – a common problem in complex multi-channel systems. This circuit offers high input impedance for negligible loading on source components, which results in less noise and distortion in the real world.
A fully complementary differential 'Class A' voltage amp with a push pull cascode output stage provides ample current to drive the triple emitter-follower output stage. This circuit topology offers very low distortion combined with high current capability.
Ultra-efficient PowerDrive Circuitry
NAD's PowerDrive circuitry measures each channel's dynamic impedance individually and computes the optimum power supply voltage required to drive the output stage for maximum power and efficiency. PowerDrive permits high dynamic power and low impedance drive capability, while maintaining ultra low (<0.03%) levels of distortion.
The M25 also incorporates NAD's acclaimed switchable "Soft Clipping" circuit. Each channel has individual over current, DC, infrasonic and ultrasonic overload sensing and protection for complete reliability under even the most severe operating conditions.
Massive Power Supply
The M25 utilizes NAD's proven Holmgren Toroidal transformer design, in a massive size, to create a power supply that offers very well regulated voltage, and truly massive amounts of current. The Holmgren transformer design utilizes proprietary low leakage field technology which is very low in both electrical noise (stray field) and physical noise (buzz).
Multiple 100,000 uF, 100V low ESR capacitors ensure a clean DC voltage supply for very low noise and truly explosive dynamics. Ultra low impedance copper buss bars are used exclusively throughout for power delivery and grounding.
Engineered to the Smallest Detailed
It is the many small details that differentiate a really great amplifier from a merely adequate one. Buffered low impedance level controls allow system fine-tuning without the distortion typical of most level control circuits.
Custom designed gold plated speaker binding posts offer multiple connector options, while maintaining a large, corrosion-free, low impedance contact area. Input jacks are also custom designed for maximum performance. Even the feet that support the M25 are engineered to filter out vibration and provide maximum performance.
The Impressive End Result
The highly developed, yet elegantly simple circuitry of the M25, is matched with a brute force power supply to create one of the most powerful Home Theatre amplifiers on the market today. Yet all this power is balanced by a liquid and transparent sonic signature that is subtlety nuanced and insightful. The M25 simply adds another dimension to surround sound that must be heard to be believed.
Owner’s Manual (2.3mb PDF)  | 
