CT Sounds AT-500.1 Class D Monoblock Car Amplifier AT-500.1D Monoblock Amplifier Power Ratings- 1 ohm at 12.8v, 500W (rms), 1000W (max) 2 ohm at 12.8v, 250W (rms), 500W (max) 4 ohm at 12.8v, 125W (rms), 250W (max) Class D Amplifier Technology