SIGA amplifiers are high efficiency switch mode audio amplifiers available in 30 and 50 watt sizes. Amplifiers have two input channels supporting dual-channel or single-channel audio applications. Amplifier project application flexibility is enhanced by provision for input levels at 1Vrms or 25Vrms. This allows SIGA amplifiers to obtain their input from a line-level signal or the output of an other 25Vrms amplifier. This feature provides great application flexibility, helping meet project requirements. Input channel selection is made through software programming and transmitted to the amplifier via a signature data circuit. This reduces wiring interconnect requirements by reducing the number of control modules needed.