L'Infonie's third album was a two-LP set, Vol. 333. Conceptually, it goes back to L'Infonie, adopting a mixed-bag format where avant-gardist rock pieces are followed by baroque music and Varèse-esque compositions. The difference is: this time it works a lot better. The first record is made of one continuous 40-minute piece, "Paix" (Peace; on both sides of the record itself, the track is designated by the wrong title "L'Infonie"). A Walter Boudreau composition, "Peace" is made of 50 sections. Thanks to the presence of a strong lead guitar (Michel Lefrançois) and rhythm section (Jacques Valois on bass and Ysengourd Knohr), the music is akin to progressive rock. Compositional elements are taken from Boulez' Ensemble Inter-Contemporain, free jazz and rock. A recurring guitar theme holds the piece together and two parts including vocals by Raôul Duguay over a rock foundation are an indication of what the latter's solo material will sound like (his first album, Alllô Tôulmônd, will be released in 1975). All in all, "Paix" is a complex and engaging piece of music, although it remains listener-friendly. (L'Infonie will record another version in 1974, released on Vol. 3333.)
The second record is less remarkable, although there are nice plays on contrasts. Bach's "Concerto in D Minor" gets a very polite orchestration by Boudreau. More interesting is a rock jam, unannounced on the track list (hidden tracks were rare during the LP era) punctuated by a vocal improvisation by Duguay. "Ubiquital 1" is a serious orchestral piece reminiscent of Varèse (Boudreau will later become the leader of the Société de musique contemporaine du Québec - the Quebec Contemporary Music Society). It has nice moments, but suffers from bad recording conditions. "La Toune Platte" (The Boring Tune), recorded live, is a bad attempt at translating to record the atmosphere of an Infonie show. But Vol. 333, in spite of limited recording facilities, remains L'Infonie's best and most representative album.