“How sharper than a serpent’s tooth it is to have a thankless child.” For decades, fans have been celebrating Gypsy as “the King Lear of the American musical theater.” Sounds a little silly, yet given the two underage vaudevillians June and Louise’s resentments again their imperious stage mother, the comparison sort of applies, and in the London revival of 2015, Imelda Staunton’s Momma Rose made it real. Yet this “mother of all musicals”—book by Arthur Laurents, music by Julie Styne, lyrics by Stephen Sondheim—is or ought still to be a musical, just as Canada Dry, “the champagne of ginger ales,” is still ginger ale. Or so we thought until we caught the six-time Tony winner Audra McDonald in George C. Wolfe’s current Broadway reboot, which overdelivers so vastly as to torpedo the genre. In private conversations, two of America’s most cherished living composers—one based on Broadway, the other in opera houses around the nation and the world—both opined that McDonald’s voice isn’t right for the score. Why not? Because unlike the force of nature Ethel Merman, for whom the role of Momma Rose was written, McDonald is not a belter. Very true: the velvety richness of her soprano turns numbers into arias, even as her Method acting (if that’s what it is) teleports us from the Orpheum circuit to a cave of the heart. In the showstoppers “Everything’s Coming Up Roses” and “Rose’s Turn,” McDonald gives full-fledged mad scenes. Sitting still, not uttering a word, the color drained from her features, she conveys her own “Never, never, never, never, never.” —Matthew Gurewitsch