Opera News commented that while his voice may have "lacked the sheer beauty [of other baritones], his performances had an Italianate urgency and forthright thrust that were unique, which established himself as a powerful, striking presence.

[2] Colzani made his stage debut in 1947 at the Teatro Comunale Bologna, as the Herald in Wagner's Lohengrin alongside Renata Tebaldi who was making her first appearance at that opera house singing Elsa.

[1] A few years later he was invited back to that house to sing the title role in Verdi's Rigoletto, a performance which greatly rose his profile as an opera singer.

[3] He took part in the creation of Darius Milhaud's David, in 1955, and sang Thoas in Gluck's Iphigénie en Tauride, opposite Maria Callas in 1957.

[3] In March 1960 Colzani was approached by Rudolf Bing, General Manager of the Metropolitan Opera in New York City, with an invitation to join the roster at the Met after the sudden death of Leonard Warren during a performance of La forza del destino left a vacancy at the house.

[1] He agreed and on April 7, 1960, Colzani made his debut at the Met in the title role of Verdi's Simon Boccanegra with Renata Tebaldi as Amelia, Richard Tucker as Gabriele Adorno, Jerome Hines as Jacopo Fiesco, and Dimitri Mitropoulos conducting.

"[1] His final and 272nd performance at the Met was on February 16, 1978, as Michonnet in Adriana Lecouvreur with Montserrat Caballé in the title role, José Carreras as Maurizio, Mignon Dunn as Princess di Bouillon, and conductor Jesús López-Cobos.