Features
Controls
Connections
Specifications

Features

Overview: The M25 is seven individual mono block amplifiers in one chassis, each using a balanced junction FET input stage to eliminate cross-talk, resulting in exceptionally low levels of noise and distortion. The power rating of 160 watts (continuous) x 7 is taken with all channels driven simultaneously into a 4Ω or 8Ω load, from 20Hz to 20kHz, at the rated distortion of 0.03%. The M25 can deliver its full-rated power for long periods; custom heat sinks and temperature regulated, variable speed cooling fans work to keep the amp running cool under the most extreme conditions. The M25 utilizes NAD's Holmgren Toroidal transformer design, in a massive size, to create a power supply that offers very well regulated voltage, and large quantities of current. The transformer design utilizes proprietary low leakage field technology which is very low in both electrical noise (stray field) and physical noise (buzz). NAD also uses an electronic ground isolation circuit to prevent ground loop noise in the system, a common problem with many complex multi-channel systems. The M25 delivers lifelike sound levels even in large home theaters; it meets THX's most stringent Ultra 2 certification level.

PowerDrive: NAD's PowerDrive technology 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.

Soft Clipping: NAD's Soft Clipping circuit gently limits the output of the M25 to minimize audible distortion when the amplifier is over-driven. Each channel is individually protected and has its own front panel LED, which turns red when the circuit engages. While Soft Clipping can be left on at all times to reduce the likelihood of audible distortion from excessive volume settings, you can also turn the circuit off for critical listening if you prefer.

Input Level: The amplifier is equipped with separate input level controls for each channel. At the full clockwise position the gain conforms to THX Ultra2 standards. Adjusting the levels may be necessary when using speakers of different efficiencies or to extend the volume control range of the preamp.

Turn-on Trigger: The M25 can be turned on automatically using the 3.5mm +12 volt trigger input on the rear panel.

Controls

Front Panel:

• Power: toggle between power on and standby

Rear Panel:

• Level: each channel has a rotary input level knob
• Soft Clipping: on/off
• 12 Volt Trigger: on/off

Connections

Rear Panel:

• Speakers: the seven pair of speaker binding posts will accept single banana plugs, pin connectors, spade lugs up to 0.48" wide, and bare wire up to 10 gauge
• Inputs: each channel has a single RCA input
• 12 Volt Trigger Input: 3.5mm mini-jack; turn the amp on/off along with another component
• Ground: terminal for grounding the chassis of the amp
• AC Input: 3-pole IEC power input for use with included cord (or optional upgraded cord)

Specifications

Amplifier Section:

• Continuous Power: 160 watts x 7 into an 8Ω or 4Ω load, 20 Hz - 20 kHz, no more than 0.03% THD, all channels driven simultaneously
• Dynamic Power:
  • 8Ω: 220 watts x 7
  • 4Ω: 350 watts x 7
  • 2Ω: 460 watts x 7
• Rated Distortion: 0.03% (20 Hz - 20 kHz)
• Signal/Noise:
  • >96 dB (ref 1 watt)
  • >118 dB (ref 160 watt)
• Damping factor: >180 (ref 8Ω, 50 Hz)
• Frequency Response:
  • +/- 0.02 dB: 20 Hz-20 kHz
  • - 3 dB: 3 Hz-70 kHz
• Input impedance: 1 MΩ + 180 pF
• Input sensitivity: 1.25 volts (+/- 50mV at rated power into 8Ω)
• Voltage gain: 29 dB
• Power Requirement: AC 120V 60Hz
• Weight: 96.3 lbs (43.7 kg)