QA108a line array system features Class D amplifiers with switch mode power supply, delivering 400W RMS LF and 100W RMS HF. Built-in DSP provides crossover, equalization and component protection. The DSP has four-position switch allowing users to select between four different EQ curves, with each selection dependent on number of cabinets used, either one, two, four, eight or as many as 12 speakers. Rotary potentiometer adjusts volume/gain level. Switchable HP filter can be engaged when QA108a cabinets are used in combination with QA118sa active subwoofers.