To provide a technology for improving tone quality in a modulated DA converter, while suppressing cost rise as much as possible.

At an audio processing apparatus 10, a digital signal is modulated by a modulator 20 and amplified by a class D amplifier 60 to output to a load 12 such as a speaker. At this point, the output of the class D amplifier 60 is fed back to the modulator 20 indirectly. In order to remove distortion component using a comparatively low speed AD converter as an AD converter needed in the feedback, a class D amplifier emulator 30 is arranged at the modulator 20, wherein the emulator simulates the class D amplifier 60 where distortion generates. In addition, the class D amplifier emulator 30 updates various parameters by learning so that they may become suitable. Thereby, distortion compensation can be performed more effectively.