In a backup system 310, 340, 350, or 360, a controller 300 controls operation of a multi-source audio apparatus MMSA. An operation status holder 310 holds operation status information Dbk of the multi-source audio apparatus MMSA. A non-volatile memory 340 stores the operation status information Dbk. A capacitor 360 as a power storage means stores part Pt of operating power. An operating power detector 350 (Sps) detects whether or not the operating power is being supplied. An operation status information write device 310 selectively writes the operation status information Dbk into the non-volatile memory 34 depending on whether or not the operating power is being supplied.