An audio device and an output method thereof are provided. The audio device includes: an envelope detector configured to detect an envelope of an input audio signal; a power supply which includes a linear power supply (LPS) and a switching-mode power supply (SMPS); an amplifier configured to amplify the input audio signal; an output unit configured to output the audio signal amplified by the amplifier; and a controller configured to compare a voltage level of the detected envelope with a preset level, select one of the LPS and the SMPS based on a result of the comparison, and control the power supply to supply power from the selected one of the LPS and the SMPS to the amplifier.