A switching power amplifier (400, 800) comprising: a pulse width modulation signal generation unit to convert an input audio signal into a PWM signal having a predetermined carrier frequency; a power amplification unit; an error correction and frequency modulation unit (420, 810) to correct a difference between the PWM signal (V 1, S1) output from the PWM signal generation unit and a power-amplified PWM signal (V 5) from a gain-control negative feedback path; wherein said power-amplified PWM signal comprises a switching frequency component for driving the power amplification unit; the error correction and frequency modulation unit comprising: an operational amplifier for generating a corrected PWM signal by calculating said difference between the PWM signal and the power-amplified PWM signal, and a self-oscillation negative feedback path to act together with the operational amplifier as a low-pass filter unit to remove from the corrected PWM signal a high-frequency component comprising both said predetermined carrier frequency and said switching frequency component thereby to provide a filtered PWM signal corresponding to said audio signal, and to add a new switching frequency component to the filtered PWM signal wherein said switching frequency is higher in frequency than said audio signal and is different in frequency from the predetermined carrier frequency, thereby to provide a modulated PWM signal (V 4, S2); and said power amplification unit configured to amplify a power of the modulated PWM signal using said switching frequency thereof, and to output the result as said power-amplified PWM signal to the gain-control negative feedback path. a pulse width modulation signal generation unit to convert an input audio signal into a PWM signal having a predetermined carrier frequency; a power amplification unit; an error correction and frequency modulation unit (420, 810) to correct a difference between the PWM signal (V 1, S1) output from the PWM signal generation unit and a power-amplified PWM signal (V 5) from a gain-control negative feedback path; wherein said power-amplified PWM signal comprises a switching frequency component for driving the power amplification unit; the error correction and frequency modulation unit comprising: an operational amplifier for generating a corrected PWM signal by calculating said difference between the PWM signal and the power-amplified PWM signal, and a self-oscillation negative feedback path to act together with the operational amplifier as a low-pass filter unit to remove from the corrected PWM signal a high-frequency component comprising both said predetermined carrier frequency and said switching frequency component thereby to provide a filtered PWM signal corresponding to said audio signal, and to add a new switching frequency component to the filtered PWM signal wherein said switching frequency is higher in frequency than said audio signal and is different in frequency from the predetermined carrier frequency, thereby to provide a modulated PWM signal (V 4, S2); and an operational amplifier for generating a corrected PWM signal by calculating said difference between the PWM signal and the power-amplified PWM signal, and a self-oscillation negative feedback path to act together with the operational amplifier as a low-pass filter unit to remove from the corrected PWM signal a high-frequency component comprising both said predetermined carrier frequency and said switching frequency component thereby to provide a filtered PWM signal corresponding to said audio signal, and to add a new switching frequency component to the filtered PWM signal wherein said switching frequency is higher in frequency than said audio signal and is different in frequency from the predetermined carrier frequency, thereby to provide a modulated PWM signal (V 4, S2); and said power amplification unit configured to amplify a power of the modulated PWM signal using said switching frequency thereof, and to output the result as said power-amplified PWM signal to the gain-control negative feedback path.