Chorister was an enormously difficult job even when the Met’s repertory extended from Handel through Mozart, Verdi, Wagner and Puccini to the middle of the 20th century. But as the company has taken on far more contemporary opera over the past two decades — in idioms as diverse as the time-stopping repetitions of Philip Glass’s “Satyagraha” and “Akhnaten” and the dense dissonance of Thomas Adès’s “The Exterminating Angel” — the demands have increased. That the chorus’s quality has increased along with them owes a great deal to Palumbo.

“When we started ‘Satyagraha,’ everyone was kind of skeptical,” said Jean Braham, a chorister since the late 1990s. “And by the end it really felt like a Zen experience. It was amazing. And Donald’s preparation of it really made that possible for us.”

Perhaps the most remarkable thing about Palumbo’s ascent to the pinnacle of his profession — “we all aspire to be like Donald,” said Michael Black, Lyric Opera of Chicago’s current chorus master — is that he has no formal musical training. He fell in love with opera as a boy growing up in Rochester, N.Y., played some piano and sang in his school chorus. But as an undergraduate at Boston University, he studied chemistry.

After graduating, though, he moved to Vienna, where he turned toward music, soaking up the fertile opera scene of the early 1970s and singing a few times in choruses conducted by Herbert von Karajan. “It was in the day when Karajan and Georg Solti were the two poles,” Palumbo said. “And I became kind of absorbed by Karajan’s style, this rounder, mellower, deeper quality of sound.”

One of Palumbo’s catchphrases is “never push your voice past the point of beauty.” That search for a warm, blended, refined sound blossomed when he returned to the United States and took work as a pianist for a prominent voice teacher in Boston. And he found a parallel to the Karajan style in the old Italian school when he became the assistant to Dallas Opera’s chorus master, Roberto Benaglio.

When the Met came calling, he had been at Lyric for well over a decade, and had just finished building and decorating a new home in Chicago. “But there was no way to say no,” he said. “Not if you’re an American and you grew up listening to the Saturday Met broadcasts, if you had to get back from your practicing to turn on the radio at a certain time.”