The TOA M-243 L is a 1U EIA-standard rack-mount stereo mixer designed for installed sound applications where compact footprint and flexible routing are priorities. With two monaural inputs accepting either microphone or line-level signals and four stereo inputs covering both RCA and phone jack sources, the M-243 L handles a wide range of input types without an external preamplifier or DI stage. Two monaural outputs and one stereo output give integrators three discrete output paths, and internal switch settings allow the monaural outputs to operate as sum outputs off the stereo bus, adding routing flexibility without additional hardware. For AV integration in conference rooms, paging systems, background music installations, and small fixed venues, the M-243 L addresses common reliability requirements directly. A built-in limiter prevents clipping under excessive input levels, and an automatic muting circuit cuts the stereo output the moment a monaural input signal is detected, which is useful in paging-over-music scenarios. A high-pass filter and PAD option on the monaural input are accessible via internal switches, allowing the installer to configure the unit for the space without external outboard gear. A recording output with high and low frequency equalization on the stereo channel rounds out the feature set for applications that require local recording or zone feed. Color-coded, interchangeable knobs and a protective input cover make the M-243 L practical for environments where panel security and operator clarity matter. The steel and alumite construction is appropriate for permanent rack installation, and the unit ships with rack screws and rubber feet for both rack-mount and tabletop deployment.