Audio processing apparatus

1. An audio processing apparatus comprising:

a first amplification section for amplifying an expansion left audio signal whish is one of an outer left audio signal, an upper left audio signal and a center left audio signal, or a left audio signal for Bi-Amp;

a second amplification section for amplifying an expansion right audio signal whish is one of an outer right audio signal, an upper right audio signal and a center right audio signal, or a right audio signal for Bi-Amp;

a third amplification section for amplifying a surround back left audio signal;

a fourth amplification section for amplifying a surround back right audio signal;

a first speaker terminal that outputs the expansion left audio signal or the left audio signal for Bi-Amp;

a second speaker terminal that outputs the expansion right audio signal or the right audio signal for Bi-Amp;

a third speaker terminal that outputs the surround back left audio signal;

a fourth speaker terminal that outputs the surround back right audio signal; and

switching section for causing the first amplification section to amplify the expansion left audio signal and supply the amplified expansion left audio signal to the first speaker terminal and causing the second amplification section to amplify the expansion right audio signal and supply the amplified expansion right audio signal to the second speaker terminal when the Bi-Amp function is not used; and causing the first amplification section to amplify the left audio signal for Bi-Amp and supply the amplified left audio signal for Bi-Amp to the first speaker terminal and causing the second amplification section to amplify the right audio signal for Bi-Amp and supply the amplified right audio signal for Bi-Amp to the second speaker terminal when the Bi-Amp function is used.

2. The audio processing apparatus according to claim 1 , wherein the third amplification section amplifies the surround back left audio signal or a center audio signal for Bi-Amp;

the third speaker terminal outputs the surround back left audio signal or the center audio signal for Bi-Amp, and

the switching section causes the third amplification section to amplify the surround back left audio signal and supply the amplified surround back left audio signal to the third speaker terminal when the Bi-Amp function is not used; and causes the third amplification section to amplify the center audio signal for Bi-Amp and supply the amplified center audio signal for Bi-Amp to the third speaker terminal when the Bi-Amp function is used.

3. The audio processing apparatus according to claim 2 , wherein when the Bi-Amp function is used, the switching section causes the fourth amplification section to amplify the adding signal that is a signal produced by adding the surround back left audio signal and the surround back right audio signal and supply the amplified adding signal to the fourth speaker terminal.

4. The audio processing apparatus according to claim 1 , wherein the third amplification section amplifies the surround back left audio signal or the surround left audio signal for Bi-Amp;

the fourth amplification section amplifies the surround back right audio signal or the surround right audio signal for Bi-Amp;

the third speaker terminal outputs the surround back left audio signal or the surround left audio signal for Bi-Amp,

the fourth speaker terminal outputs the surround back right audio signal or the surround right audio signal for Bi-Amp, and

the switching section causes the third amplification section to amplify the surround back left audio signal and supply the amplified surround back left audio signal to the third speaker terminal and the fourth amplification section to amplify the surround back right audio signal and supply the amplified surround back right audio signal to the fourth speaker terminal when the Bi-Amp function is not used; and causes the third amplification section to amplify the surround left audio signal for Bi-Amp and supply the amplified surround left audio signal for Bi-Amp to the third speaker terminal and the fourth amplification section to amplify the surround right audio signal for Bi-Amp and supply the amplified surround right audio signal for Bi-Amp to the fourth speaker terminal when the Bi-Amp function is used.

5. The audio processing apparatus according to claim 1 , further comprising:

a fifth speaker terminal that outputs the second expansion left audio signal whish is one of the outer left audio signal, the upper left audio signal and the center left audio signal and is different from the expansion left audio signal;

a sixth speaker terminal that outputs the second expansion right audio signal whish is one of the outer right audio signal, the upper right audio signal and the center right audio signal and is different from the expansion right audio signal; and

channel determination section for determining which one of a combination of the expansion left audio signal and the expansion right audio signal and a combination of the second expansion left audio signal and second expansion right audio signal is included in multichannel audio data, wherein

in case that the Bi-Amp function is not used, the switching section causes the first amplification section to amplify the expansion left audio signal and supply the amplified expansion left audio signal to the first speaker terminal and causes the second amplification section to amplify the expansion right audio signal and supply the amplified expansion right audio signal to the second speaker terminal when the combination of the expansion left audio signal and the expansion right audio signal is determined to be included; and causes the first amplification section to amplify the second expansion left audio signal and supply the amplified second expansion left audio signal to the fifth speaker terminal and causes the second amplification section to amplify the second expansion right audio signal and supply the amplified second expansion right audio signal to the sixth speaker terminal when the combination of the second expansion left audio signal and second expansion right audio signal is determined to be included.