Around 1578 he moved to Venice, where he met Claudio Merulo, Gioseffo Zarlino and Costanzo Porta (who was also a friar minor conventual), and he probably studied with each of them.
In 1610 from Gubbio he dedicated the second part of his treatise Il Transilvano to Leonora Orsini Sforza, niece of Grand Duke Ferdinand I of Tuscany.
[2] Diruta's major work is a treatise in two parts on organ playing, counterpoint, and composition, entitled Il Transilvano (The Transylvanian) published for the first time in 1593; it is in the form of a dialog with Istvan de Josíka, a diplomat from Transylvania whom Diruta met during one of Josíka's missions to Italy.
Unlike Fux, he defines a less-rigorous kind of counterpoint that was adequate for improvisation; for example it neither requires contrary motion nor prohibits successive perfect consonances.
The Prima parte also includes toccatas by other composers of the time, chosen for their musical and didactic value: Claudio Merulo, Andrea Gabrieli, Giovanni Gabrieli, Luzzasco Luzzaschi, Antonio Romanini, Paolo Quagliati, Vincenzo Bellavere and Gioseffo Guami.