Each channel combines an Expander/Gate, a Compressor/Limiter and a fully adjustable Enhancer. This unique circuit reduces noise, increases loudness and recovers high frequencies that might otherwise be compromised when audio is heavily compressed. The Spectra switch adds a mid-band boost to the detector circuit to help smooth out harsh vocals. The Expander/Gate features a variable Threshold control and switchable (fast/slow) Release time. The Gate's operation is easily visible with twin (open and closed) LEDs. The S com's Compressor/Limiter controls include Threshold, Ratio, Attack, Release, and Output. The Auto function continuously analyzes the audio input, and automatically adjusts the attack and release parameters based on the changing level. A Key input and Key Listen feature provides for external triggering, or EQ, of dynamically processed signals.