VM Audio ECD4200.1 Encore 4200W 1 Ohm Class D Amp Digital Mono Power Amplifier Mono Power Subwoofer Car Amplifier - Hyper-Digital Class D Exclusive Robust High-Cycle DC-to-DC PWM Power Conversion Four-Stage Regulated Synergistic High Voltage Rail Performance Sophisticated Noise Free Single Star Ground System Strategic Side-to-Side Air Flow Thermal Cooling Chassis Ventilation