Cos was a Belgian avant-jazz-rock band that released four albums on IBC between 1974 and 1979, followed by two 1983–84 titles on Lark. Keyboardist Charles Loos (Abraxis/Julverne) appears on the first and third albums, Postaeolian Train Robbery and Babel. Former Placebo keyboardist Marc Moulin produced their 1976 release Viva Boma, which features sundry instrumentation from Aksak Maboul mastermind Marc Hollander.

Members: Pascale Son (vocals, oboe), Daniel Schell (guitar, flute, sound effects), Charles Loos (keyboards, piano), Marc Hollander (keyboards, bass clarinet, alto saxophone, devices), Alain Goutier (bass), Philippe Allaert (drums), Mutsari (bass)

Cos formed as Classroom, assembled by musician/composer Daniel Schell (b. Schellekens, 1944) and his vocalist wife Pascale “Son” (née De Trazegnies, b. 1948). Schell played on a 1969 jazz single by the Brussels Art Quintet, issued on the acronymic self-press BAQ.

In 1973, Classroom included ex-Waterloo bassist Jean-Paul Musette, veteran jazz drummer Robert Pernet (1940–2001), and BAQ vibraphonist Jean-Pierre Destrée. With producer Jean Huysmans (Placebo, Doctor Downtrip), they recorded three Schell originals: “Sur Deux,” “L’Admirable Amas Cellulaire Orangé,” and the 10-minute “Achille.” On a fourth song, “La Partie D’Echecs,” Schell employed drummer Jean-Luc Van Lommel and pianist Charles Loos.

In 1974, Classroom reconfigured as Cos with Schell, Son, Loos, bassist Alain Goutier, drummer Robert Dartsch, and percussionist Steve Leduc. That August, they entered Start Studio in Brussels to record their first album.