Premise: Mars Audiac Quintet is the third album by the band Stereolab, released in August 1994. Initial releases of the CD came with bonus two-track disk, the double vinyl album came with a 7". During the recording of the album, guitarist Sean O'Hagan left as a full-time member to form his own group, while keyboardist Katharine Gifford was added.
Hypothesis: The guitarist left while the keyboardist was added.