A digital speaker system comprising: a plurality of speakers (2, 21a to 23a, 2c, 21d, 22d, 3, 3c, 3d, 4, 4c, 4d), each of the plurality of speakers having a plurality of voice coils, the number of voice coils associated to the left channels being equal to the number of voice coils associated to the right channels; a signal processing circuit (10, 10a, 10b, 10c, 10d) that is configured to output a plurality of right-channel digital signals and a plurality of left-channel digital signals, the signal processing circuit comprising one digital amplifier for each of the channels, wherein each digital amplifier is configured to amplify the respective digital signal, wherein the digital signals of the respective channels are input to the voice coils from the signal processing circuit through the signal lines which are individually provided to each of the channels, characterized in that: at least one of the plurality of speakers (2, 2c, 21d, 22d) is operated to function as a center speaker, the center speaker including a single bobbin that is equipped with a plurality of voice coils associated to the right channels and a plurality of voice coils associated to the left channels; the signal processing circuit is configured to input right-channel digital signals to the right-channel voice coils and left-channel digital signals to the left-channel voice coils of the center speaker; both the right-channel digital signals and the left-channel digital signals are input to the respective voice coils of the center speaker and combined at the single bobbin of the center speaker, whereby the center speaker is configured to output monaural sound; and the plurality of speakers comprises a right speaker (3, 3c, 3d) to which one or plural right-channel digital signals that are not input to the center speaker and out of the plurality of right-channel digital signals output by the signal processing circuit are input to output right sounds, and a left speaker (4, 4c, 4d) to which one or plural left-channel digital signals that are not input to the center speaker and out of the plurality of left-channel digital signals output by the signal processing circuit are input to output left sounds. a plurality of speakers (2, 21a to 23a, 2c, 21d, 22d, 3, 3c, 3d, 4, 4c, 4d), each of the plurality of speakers having a plurality of voice coils, the number of voice coils associated to the left channels being equal to the number of voice coils associated to the right channels; a signal processing circuit (10, 10a, 10b, 10c, 10d) that is configured to output a plurality of right-channel digital signals and a plurality of left-channel digital signals, the signal processing circuit comprising one digital amplifier for each of the channels, wherein each digital amplifier is configured to amplify the respective digital signal, wherein the digital signals of the respective channels are input to the voice coils from the signal processing circuit through the signal lines which are individually provided to each of the channels, characterized in that: at least one of the plurality of speakers (2, 2c, 21d, 22d) is operated to function as a center speaker, the center speaker including a single bobbin that is equipped with a plurality of voice coils associated to the right channels and a plurality of voice coils associated to the left channels; the signal processing circuit is configured to input right-channel digital signals to the right-channel voice coils and left-channel digital signals to the left-channel voice coils of the center speaker; both the right-channel digital signals and the left-channel digital signals are input to the respective voice coils of the center speaker and combined at the single bobbin of the center speaker, whereby the center speaker is configured to output monaural sound; and the plurality of speakers comprises a right speaker (3, 3c, 3d) to which one or plural right-channel digital signals that are not input to the center speaker and out of the plurality of right-channel digital signals output by the signal processing circuit are input to output right sounds, and a left speaker (4, 4c, 4d) to which one or plural left-channel digital signals that are not input to the center speaker and out of the plurality of left-channel digital signals output by the signal processing circuit are input to output left sounds. at least one of the plurality of speakers (2, 2c, 21d, 22d) is operated to function as a center speaker, the center speaker including a single bobbin that is equipped with a plurality of voice coils associated to the right channels and a plurality of voice coils associated to the left channels; the signal processing circuit is configured to input right-channel digital signals to the right-channel voice coils and left-channel digital signals to the left-channel voice coils of the center speaker; both the right-channel digital signals and the left-channel digital signals are input to the respective voice coils of the center speaker and combined at the single bobbin of the center speaker, whereby the center speaker is configured to output monaural sound; and the plurality of speakers comprises a right speaker (3, 3c, 3d) to which one or plural right-channel digital signals that are not input to the center speaker and out of the plurality of right-channel digital signals output by the signal processing circuit are input to output right sounds, and a left speaker (4, 4c, 4d) to which one or plural left-channel digital signals that are not input to the center speaker and out of the plurality of left-channel digital signals output by the signal processing circuit are input to output left sounds.