JL Audio XD600/1 Specifications & Features Amazingly small in size, but huge in audio performance, the JL Audio XD amplifiers are the perfect solution for space-conscious installations or for anyone seeking affordable excellence in a mobile amplifier. JL Audio&s exclusive Nex D™ switching technology achieves total amplifier efficiencies exceeding 80%, which means far less heat & less strain on your vehicle&s electrical system than a conventional large amplifier. This efficiency advantage, combined with state-of-the-art microelectronic components allows us to use very compact unitary cast alloy heat sinks. As with their more expensive HD siblings, XD&s also deploy JL&s Advanced Thermal Rollback System to completely eliminate annoying thermal shut-down events. Beneath every XD&s removable control cover, you will find studio-grade signal processing with fully variable crossover filters. Also included are our no