The Reference 300 Watt subwoofer amplifier 311a features a 12dB per octave electronic crossover, allowing you to optimize bass performance based on enclosure type and subwoofer selection. High-output PWM MOSFET power supply ensures optimum power delivery into numerous impedances with low distortion. Full-range preamp outputs facilitate use of multiple amplifiers without the need for noisy and expensive adapters or signal splitters. Dynamic Bass Optimization (DBO) circuit provides variable filtering with adjustable "Q" below 100Hz, far beyond conventional "Bass EQ" circuits, by allowing the low-frequency output to be optimized for specific subwoofer applications.