Between 1958 and 1960, three prominent figures of the European post-war musical avant-garde premiered major works for spatially distributed orchestral groups: Pierre Boulez’s Doubles, Karlheinz Stockhausen’s Gruppen and Carré, and Henri Pousseur’s Rimes pour multiples sources sonores. This period coincides with the introduction of stereo long-playing records that led to the mass distribution of stereo sound technology, buoyed by an aggressive marketing campaign. To what extent were listeners’ experiences of spatialized works like Doubles, Gruppen and Rimes informed by their new familiarity with stereo sound? How did composers respond to listeners’ expectations about, and understanding of, stereo in their spatialized works? This chapter evaluates the extent to which an allusion to the technology of stereophony was inscribed into these works, an inscription that might include both ways audiences were inclined to hear stereophonic effects in these works and composers might have reacted in their works to these expectations.