Class-D amplifiers overcome the inefficiencies of traditional Class-A or AB amplifiers. Pioneers Class-D amps transform very little power into heat while a very high percentage of the power supply (67 %) is transformed into the load. This results in a very compact amp which needs little input power to produce very high output power. The Class-D amplifiers PWM (Pulse Width Modulator) modulates the original audio input signal with another signal which has a much higher fixed frequency. The result is a digital signal which contains the input signal and a band of frequency components around the modulation frequency. A LPF (Low Pass Filter) will then filter out the high frequency pulses and the resulting amplified output signal is then sent to the subwoofer and/or speakers.