User operates a selection switch to instruct temporary activation of an application. For the application of which the temporary activation has been instructed, a CPU of a console allocates resources necessary for signal processing by a DSP of an engine and for a parameter editing function of the console. In the DSP, a bypass parameter is set to ON. Thus, there is provided a state capable of accepting various parameter setting operation related to the application, but the signal processing based on the application program is prevented from being started in a substantive manner. In response to a full activation instruction of an application via a full activation instruction switch, the bypass parameter is set to OFF, so that audio signal processing based on the application can be started. In this way, preparatory work for setting parameters related to the application can be performed efficiently.