A signal processing apparatus performs a signal processing using a plurality of signal processing modules associated with a corresponding plurality of signal processing functions. The plurality of signal processing modules are graphically displayed. One or more of a plurality of available commands are received from a user. A virtual connection state of the plurality of signal processing modules is set that defines connections among the inputs and outputs of the plurality of signal processing modules. The virtual connection state is stored and managed. A sequence of corresponding signal processing functions is determined based on the virtual connection state. Signal processing is performed in accordance with the determined sequence of signal processing functions.