Pioneer introduced the M-90 Reference Power Amplifier in 1987, to be used in conjunction with the C-90 Reference Control Amplifier.  In the January 1987 issue of Stereo Review that ran the  "Not Evolutionary-Revolutionary" advertisement, here is what Pioneer said about the M-90:

"The M-90 is a superb high-power stereo amplifier, utilizing dual-mono construction.  It is conservatively rated at 200 W/CH into 8 ohms and delivers 800 W/CH of dynamic power at 2 ohms.  The wide dynamic range of the digital sources can now be reproduced effortlessly, with any loudspeakers.  The M-90's high current capacity of 47 amps can handle the challenge of the most complex speaker loads.  To further enhance S/N ratio and channel separation, relay-operated electronic switches and a long shaft volume control keep the length of signal paths down to a minimum.  Why include a high quality volume control on a power amp?  To pursue the straight wire-with-gain philosophy when using a CD player connected directly.  Pure sound, redefined."

The M-90 was virtually distortion-free, having only 0.003% THD from 20-20K Hz @ 8 ohms, and had a S/N ratio of 125 dB!  (See the complete specifications at bottom of page.)   The M.S.R.P. for the M-90 was $950.00.  It was superceded by the M-91 in 1989.

M-90 Specifications
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