More power is always better when it comes to sound quality. Power is required not only to play loudly, but also to play cleanly without audible distortion. When an amplifier is asked for more power than it was designed to deliver, it can only respond with distortion. Fortunately the M25 is one of the most powerful amplifiers on the market today designed for home use. With a minimum of 160 continuous watts per channel, all channels driven simultaneously, from 20Hz to 20kHz at rated distortion of 0.03%, the M25 easily delivers lifelike sound levels even in large home theatre rooms. It handily meets THX’s most stringent certification level, Ultra 2.
Unlike most surround sound receivers (NAD’s own receivers are a rare exception) that only rate power with 1 or 2 channels running, or use very short term measurements, the M25 can deliver its full rated power continuously for hours on end. Custom designed heat sinks and thermostatically regulated variable speed fans keep things cool under the most severe operating conditions. A unique fan circuit that tracks signal level, actually shuts down the fans during quiet passages to prevent any mechanical noise from interfering with the program material. 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.
The M25 is comprised of 7 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.
Continuous Power, 20Hz-20kHz, all channels driven simultaneously at 4/8 ohms > 7 x 160 W (22.0 dBW)
Rated Distortion (THD 20Hz-20kHz) 0.03%
Clipping Power (0.1% THD) >180 W
IHF dynamic headroom at 4 ohms 3.9dBW
IHF dynamic power at 8 ohms >220 W (23.4 dBW)
IHF dynamic power at 4 ohms >385 W (25.9 dBW)
IHF dynamic power at 2 ohms >485 W (26.9 dBW)
Damping Factor – ref. 8 ohms, 50Hz >180
Input Impedance 1 Mohms;C = 180 pF
Input Sensitivity 1250mV+/-50mV
Voltage Gain 29.0dB
Frequency Response 20 Hz – 20 kHz ±0.2 dB
Signal/Noise Ratio – 3dB at 3 Hz/70 kHz
Dimensions (W x H x D) 435 x 200 x 466mm
Net Weight 96.3 lbs (43.7 kg)