MB Quart Discus DSC4125 500 Watt A/B Class 4-Channel Amplifier 4 x 125 W @ 4 Ohms, 4 x 250 W @ 2 Ohms, 2 x 500 W @ 4 Ohms System stability with oversized Pulse Width Modulation (PWM) digital power supplies and high-speed MOSFET output devices for superior sound Ultra-flexible and variable adjustable active crossover network; bass equalizer circuit up to +12 dB and full-range preamp outputs Tandem-core toroidals for extreme ruggedness and high-grade electrical components