The strong German influence in Gnecchi’s music may have been one of the factors contributing to his neglect in Italy itself. What is certain, Mr. Iannelli said, is that Gnecchi’s family, which had been close to the Italian monarchy and sold fabric that would be made into German parachutes in World War I, lost prestige after the war.

Mr. Iannelli just finished a new working edition of Gnecchi’s “Giuditta,” an opera about the biblical drama of Judith and Holofernes left partly unfinished. Like “Cassandra,” it was created in collaboration with the librettist Luigi Illica, best known for his work with Puccini. In both operas, Mr. Iannelli said, Gnecchi’s use of the chorus is especially visionary.

“In a Greek tragedy, the chorus is a commentator, the voice of the audience,” Mr. Iannelli said. Gnecchi translated that concept musically, through the use of Greek modes in the choral parts to “Cassandra,” which are often splintered into six or eight parts. Certain scenes feature spatially separated choirs, creating the illusion of depth and three-dimensional reality that was so important to verismo composers. In fact, Mr. Iannelli said, he found a letter Gnecchi wrote to Illica in which he suggested arranging chorus members in “Cassandra” behind the audience — a “surround sound” effect that would be realized in different musical forms only decades later. In this manner, Mr. Iannelli said, “the choir really becomes the voice of the audience.“

Mr. Gursky drew attention to the care with which Gnecchi constructed the large scenes in this Greek drama. “It’s kaleidoscopic the way he composes: Various elements go in and out of focus. You have the different choral groups along with principals going in and out, and there is a very dense use of leitmotifs in the orchestra. At first hearing it can be overwhelming.”