A digital mixer has a custom component specified by a configuration ID. Further, the same configuration ID is provided to another custom component for ensuring compatibility of scene data which is used for operating the custom component. When a custom component of the mixer configuration is edited, the edited custom component is provided with the same configuration ID as the initial custom component before the editing. Scene data of the initial custom component can be copied to scene data of the edited custom component or vice versa provided that their configuration IDs match with each other.