The full title of this landmark collection, Otra Musica: Tape Music, Fluxus & Free Improvisation in Buenos Aires 1963-70, says a tremendous amount this overwhelming package in & of itself. Though he has only recently come to international attention through his recordings for Hatart as a leader and with Franz Koglmann, Argentinean clarinetist and alto saxophonist Guillermo Gregorio had a fascinating earlier artistic incarnation in Buenos Aires. Heretofore totally unknown, these recordings bring to light an incredibly sophisticated sound-world of proto-electronica, Fluxus-oriented performance art and very early free improvised music, all from a virtually secret enclave of South American experimentalism. Sixteen tracks, none ever released before, with various groups including Movimiento Música Más, totally free duets with trumpeter Carlos Miralles from '64, an astounding solo alto piece from the same year. Painstakingly researched and lavishly documented, with an in-depth essay by John Corbett, loads of great photos and reproductions of two of Gregorio's 1960s paintings, Otra Musica: Tape Music, Fluxus & Free Improvisation in Buenos Aires 1963-70 will stand as one of the great archival unearthing of creative music.