The Yamaha m-40 is a high end powerful piece of equipment perfect for any home system! From the same concept as the other power amplifiers from the m and mx series with switchable class A technology, the 1st approximately 15 to 20 watts, this M40 can play in pure class A! Symmetrical construction 8 x power transistors deliver 2 x 120w The specs from the manual: continuous power per channel: 20hz-20khz 0.003% Thd 8 - 120w 0.007% Thd 6 - 145w 0.02% Thd 4 - 170 w dynamic power: 1khz 8 / 6 / 2 - 160/200/280 /390 w power bandwidth (0.03% Thd, 60 w/8) - 10 Hz-100kHz total harmonic distortion: main in to sp out, 60w/8 - 0.002% Im distortion ratio (8) - 0.003% Damping factor - (speaker a, 1 kHz) - 130 frequency response (20Hz~20kHz) - +0, -0.1dB input sensitivity/impedance - 1.07v/20k signal-to-noise ratio (ihf-a-network): (main in shorted, 5.1 K) -127dB/119dB channel separation: input shorted - 40 Hz - 106dB 1kHz - 89dB 10kHz - 70dB power supply 500 w Dimensions (w x h x d) - 435 x 1665 x 425 mm weight - 14 k In good condition, has just been professionally serviced, including 3 pairs of decent gold plated speaker terminals instead of the vulnerable, often faulty, 3-fold plastic connections.