AV1B audio-visual interface allows the line-level outputs of audio and video playback devices, etc., to be connected to microphone inputs of house or portable P.A. systems for programs in school auditoriums, lecture halls, civic meetings and corporate board rooms. The AV1B provides audio interfacing and isolation with wide response and low distortion. The AV1B’s construction and components are top-grade throughout, ensuring trouble-free operation in educational, institutional and A/V rental settings. Uni-box enclosure is formed of extruded aluminum side channels and 16-gauge steel top, bottom and end plates and is designed to protect it’s switches and connectors from accidental damage. The use of steel also provides excellent magnetic shielding for the transformer from EMI/RFI fields. The finish is durable black textured powder coat on the end plates and the side channels are black anodized aluminum. Easily readable control and connector identification graphics are incorporated into a durable Lexan® overlay on the top panel. The uniquely slotted side channels allow for stacking on top or strapping side-to-side of virtually any number of devices using the Uni-box construction.