The audio device according to the present disclosure may include a mixer that adjusts the number of channels of an inputted audio signal based on the number of speakers connected, a transmitter that transmits a test audio signal for speaker setup, to at least one speaker among the plurality of speakers, a feedback receiver that receives a signal of the outputted audio, a controller that determines an output time difference between the plurality of speakers, based on the signal of the outputted audio, and a post-processor that adds an output delay signal to the audio signal of at least one channel of a multi-channel audio signal provided to the plurality of speakers so as to synchronize the outputs of the plurality of speakers, based on the determined output time difference.