A 2channel power amplifier rated at 240 watts per channel @ 8ohms. It was built between 1979-1981 and was modeled after the M-4 which was half the power, but the design was more close to the studio and DJ rack mounted PC and PCM series which came out at about the mid seventies. The M-2 actually was rated a little higher wattage than those models, but did share the same heatsinks and some other parts. Yamaha did claim that it was a whole new design, but if the covers were taken off each one they were very close. Like the M-4 it has a switchable AC/DC input with separate RCA connectors and input level controls. It has hookups for 4 speakers which are controlled with on and off switches on the front. Specifications are as follows:
Rated output power:
240+240W (8ohm) 20Hz-30kHz @ 0.005% T.H.D.
Power band width:
10Hz-100kHz (8ohm) 0.01% T.H.D.
Input sensitivity / impedance:
1.62V (240W / 8ohm) 25kohm +-5kohm
DC input 8ohm 1W
AC input 8ohm 1W
Less than 0.004% (8ohm, 10Hz - 20kHz)
Less than 0.007% (8ohm, 50kHz)
Less than 0.01% (8ohm, 100kHz)
All in all to me, the Yamaha M-2 is a good amplifier and in my experience can drive most any speaker that is hooked up to it. I currently have one connected a set of Magnepan MG1's on the mains and another one connected to a set of Magnepan MMG's on the surround with no problem at all driving them.
The one con issue that was mentioned that they were not built for very long was not that it wasn't a good amplifier rather Yamaha came out with a new design (M-40 to M-80 series) which was easier...