A method of controlling a sound output of a first audio reproducing device that is operable in a simultaneous listening mode with a second audio reproducing device such that, in the simultaneous listening mode, each of the first audio reproducing device and the second audio reproducing device operate to output content sound based on an audio content signal streamed from a corresponding content providing device through a communication connection, according to their respective sound output settings, the method including detecting a conversation request from the second audio reproducing device; controlling the first audio reproducing device to exit the simultaneous listening mode, enter a conversation mode, and change the sound output setting of the first audio reproducing device, in response to detecting the conversation request; and controlling the first audio reproducing device to output the content sound based on the changed sound output setting while operating in the conversation mode.