To shift a sound image as desired between the positions occupied by the loudspeakers in stereo or quadraphonic reproduction.
"Just a short note to thank you for the wonderful job you did transferring my old cassette of Japanese koto music to CD. I haven't be able to find a CD version of this tape in Japan and had stopped playing it to avoid wearing it out. Within days of sending it to you I received back an excellent CD of this beloved tape at a very low cost. Thanks ..."