Over the next few years, he appeared at leading opera houses throughout Italy and Spain and was a member of a distinguished Italian operatic company which visited Buenos Aires in 1890.
De Marchi returned to Buenos Aires in 1895, 1896 and 1900 and his other roles were Raoul, Alfredo, Faust (Boito), Des Grieux (Puccini), Lohengrin, Tannhäuser, Turiddu, and Samson.
He debuted at Italy's leading opera house, La Scala, Milan, in 1898 as Stolzing in an Italian-language version of Richard Wagner's Die Meistersinger.
He proved to be a success at La Scala and was chosen by the composer Puccini to sing the coveted role of Cavaradossi in the first performance of Tosca, which occurred at Rome's Teatro Costanzi on 14 January 1900.
He sang with soprano Emma Eames as Tosca and baritone Antonio Scotti as Scarpia, with Luigi Mancinelli conducting.