The M-91 stereo power amplifier was introduced in 1991 to supercede the M-90. Visually, it was practically identical to the M-90, except for the obvious inclusion of the word ELITE on the front panel above the power meter panel. (The example shown here is missing the center, flip down panel. However, Pioneer did change the power transformers for the M-91, with a subsequent increase in weight to 60 lbs.

The specifications for the M-91 were virtually identical to those of the M-90, with 200 watts per channel into 8 ohms, from 20 Hz to 20kHz with only .003% Total Harmonic Distortion.  Its signal-to-noise ratio was an impressive 125 dB.

According to the Stereo Review Buyer's Guide which was published in February of each year, the M-91 was offered through 1998. It's list price was $1400.00 and remained there until it ceased production.

Specifications:



2-Channel Power Amplifier

200 Watts Per Channel (Stereo): 8 ohms from 20-20,000 Hz with no more than .003% Total Harmonic Distortion

Dynamic Power:

Low-Impedance Driving Capability
Non-Switching Circuit Type II
Two-Mono-Amps-In-One Design
Separate Power Supplies (Left & Right)
Direct Connection
CD Direct with Volume Control
Line-Level Inputs with Volume Control
CD, Line Output Loop for Preamplifier
Headphone Output
Speaker A/B, A + B, Off
Large Fluorescent Power Level Indicator
Elaborate Anti-Resonance and Anti-Vibration Designs:

• Twin Power Transformers Encased in
  
• Cast-Iron Housings
  
• Honeycomb Heat Sink
  
• Large Honeycomb Insulators
  
• Copper Plated Chassis and Screws
  Urushi Finish with Wood Side Panels
  Two-Year Warranty