A method, medium, and system encoding and/or decoding a multi-channel audio signal, and a method, medium, and system decoding a signal down-mixed from multi-channels to a 2-channel signal. The method of encoding an audio signal may include generating spatial cues indicating directivity information of a virtual sound source generated by at least two channel sound sources among a plurality of channels, and down-mixing the plurality of channel signals. The method of decoding an audio signal may include receiving inputs of spatial cues indicating directivity information of a virtual sound source generated by at least two channel sound sources among sound sources of a plurality of channels, and a signal down-mixed from the plurality of channel signals, and restoring the down-mixed signal to a plurality of channel signals by using the spatial cues. According to such systems, media, and methods, a multi-channel audio signal can be accurately encoded and/or decoded regardless of frequency bands.