The M-243 is an EIA Standard equipment rack (1-unit size) stereo mixer that comes with two monaural inputs, four stereo inputs, one stereo output and two monaural outputs.

• 2 monaural inputs, 4 stereo inputs, 1 stereo output, and 2 monaural outputs. Assignable each input signal to 3 output channels individually.
• Sub-input terminals for stereo output channel and each of 2 monaural output channels.
• Microphone input or line input for monaural input selectable depending on the signal level. Built-in limiter  circuitry eliminates distortion under excessive input levels. High-pass filter as well as PAD (only for MIC input) in the monaural line available by the internal switch settings.
• Peak indicator to detect clipping.
• An "Automatic Muting" circuit automatically mutes the stereo output signal by detecting the monaural input signal. (ON/OFF switchable)
• A recording output and equalizer (high and low frequencies) for the stereo output channel.
• 2 channel monaural outputs usable as sum outputs for the stereo output channel individually by the internal switch setting.
• Protective cover for protecting the setting position of each input usable as a writing plate.
• Knobs supplied in different colors and size easily replaceable depending on the intended use, improving operability of the unit.