Arnold Schoenberg’s name is synonymous with atonality and 12-tone technique. Work on his stupendous 90-minute cantata began before he embarked on that adventure but did not conclude until he was well on his way. Much of Gurrelieder looks backward, enthralled, to Wagner; later passages—including the first instance of the dicey singsong technique known as Sprechstimme—are prophetic. And there’s plenty of Mahler in the mix. As for the subject matter, imagine a Rapunzel in her tower, pouring out her soul like Isolde to a second Tristan married to a queen who will not stop at murder. But the tale does not end in death. By night, mad with grief, the monarch storms through the woods with his ghostly vassals, yielding only to the glory of the rising sun, evoked in a many-splendored chorus of bewildering complexity. It’s quite the head trip, Gurrelieder, made to order for an orchestral generalissimo like L.A.’s Gustavo Dudamel. —M.G.