The QD-4240 is a quad, four channel power amplifier amplifiers capable of driving 4 ohm loads. Their clean sound quality makes them ideal for permanent installation in professional PA systems or for portable use for live performances. Primarily designed for multi-zone use such as in bars and restaurants, where separate control of the music in several areas is required, these designs may be applicable for use in any situation where a number of low-power amplifiers are required, such as for cue-feeds, effects-loudspeakers, museum displays etc. Three models are available; each combines four separate low-impedance amplifiers in a single 2U rack-mounted case. Each amplifier has an individual input XLR/TRS "Combo" balanced input connector, a level-control with associated signal-present and clip LED’s, and 5 way binding-post speaker output terminals. For added versatility, an input-selector switch allows each pair of amplifiers to be driven either separately (stereo), with inputs in parallel (dual mono), or bridged into mono. Clip-limiters are supplied on each channel to help prevent distortion due to excessive signal levels. All units have soft-start protection circuitry and feature power, signal, protection, and clip indicators on the front panel. These amplifiers are fan-cooled with circuit-protection and turn-on delay. The quad series amplifiers are powered by 100-120VAC or 220-240VAC 50/60Hz (depending on country requirements). Used in schools, hospitals, malls, campus, transportation, correctional facilities and a variety of commercial and industrial applications.