Composer Udo Kasemets (1919–2014) emigrated to Canada in 1951 from Estonia following the Second World War, and during the 1960s undertook a number of initiatives to mobilize experimental music in Toronto. This article investigates Canavangard, Kasemets's publication series of graphic scores which appeared between 1967 and 1970. Influenced by Marshall McLuhan's spatial theory of media, Kasemets saw the transformative potential of non-standard notational practices to recalibrate the relationships between composer, performer, and listener. Kasemets's 1963 composition Trigon, which was frequently performed by his ensemble during the decade, illuminates the connections between McLuhan and experimental music. In my analysis of the work, I argue that Trigon manifestly puts into performance many of the rhetorical strategies used by McLuhan to describe the immersive, intersensory environments of post-typographic media ecologies. Kasemets believed that abandoning standard notation would have extraordinary ramifications for musical practice going forward in the twentieth century, similar to how McLuhan saw the messianic power of electronic media to destabilize the typographic universe. Canavangard, as much more than a short-lived publication series of graphic scores, maps the convergences of music, culture, and technology in post-war Canada.