To prevent noise from intruding into a line when the line used to remotely control a main control console from a remote control console is not in use.

In the case of applying acoustic control to a hall or a theater or the like by using a remote control console 201 to remotely control a main control console 207, which the remote control console 201 is not in use, a termination resistor is automatically connected to a line. When a line connector of the remote control console is disconnected, the termination resistor is automatically connected to a control line. Moreover, a control command from the remote control console disconnects the termination resistor. Or, a state of the lie is monitored to disconnect the termination resistor. When the line connector is disconnected, the line impedance reaching an open impedance is avoided so as to avoid the line from received an induced noise and to prevent the induced noise from intruding to the main control console.