A signal processing device comprising: a switching reception portion that receives, from a user, an instruction for switching a supply destination of a signal to (i) a first supply destination including a first pair of speakers , (ii) a second supply destination including a second pair of speakers different from the first pair of speakers , or (iii) a third supply destination including a third pair of speakers including both the first pair of speakers and the second pair of speakers ; a storage portion that stores an optimal setting (Ia) in association with each of the first supply destination, the second supply destination, and the third supply destination, the optimal setting (Ia) stored in association with each of the first supply destination, the second supply destination, and the third supply destination being obtained by respectively measuring characteristics of the speakers of the first supply destination, the second supply destination, and the third supply destination and; and characterized by the optimal setting (la) comprising at least one of a setting of frequency characteristics, a setting of output timing, and a setting of a volume level for optimizing the characteristics of the speaker according to the switching of the speaker; and a signal processing portion that reads out an optimal setting (la) from among optimal settings stored in the storage portion in association with the first supply destination the second supply destination, and the third supply destination and uses the read-out optimal setting (la) to process a signal to be supplied to the speakers of the first supply destination, the second supply destination, or the third supply destination according to the instruction for switching the supply destination received by the switching reception portion . a switching reception portion that receives, from a user, an instruction for switching a supply destination of a signal to (i) a first supply destination including a first pair of speakers , (ii) a second supply destination including a second pair of speakers different from the first pair of speakers , or (iii) a third supply destination including a third pair of speakers including both the first pair of speakers and the second pair of speakers ; a storage portion that stores an optimal setting (Ia) in association with each of the first supply destination, the second supply destination, and the third supply destination, the optimal setting (Ia) stored in association with each of the first supply destination, the second supply destination, and the third supply destination being obtained by respectively measuring characteristics of the speakers of the first supply destination, the second supply destination, and the third supply destination and; and characterized by the optimal setting (la) comprising at least one of a setting of frequency characteristics, a setting of output timing, and a setting of a volume level for optimizing the characteristics of the speaker according to the switching of the speaker; and a signal processing portion that reads out an optimal setting (la) from among optimal settings stored in the storage portion in association with the first supply destination the second supply destination, and the third supply destination and uses the read-out optimal setting (la) to process a signal to be supplied to the speakers of the first supply destination, the second supply destination, or the third supply destination according to the instruction for switching the supply destination received by the switching reception portion . <EOS>