Audra McDonald opened the Celebrity Series of Boston’s season at Symphony Hall on Sunday with, she announced with some relief, “a happy-dust-free concert.’’ McDonald has, of course, been nightly battling the thrall of happy dust for the past several weeks in Cambridge, headlining the American Repertory Theater’s new production of “Porgy and Bess.’’ This show, a bit of a farewell after that residency, was a complementary display of her music-theater acumen: McDonald is one of the most consummate performers there is, effortlessly intimate, casually masterly, seemingly more comfortable on stage than most people are anywhere.
With efficiently accomplished backing (drummer Gene Lewin, bassist Mark Vanderpoel, and pianist/music director Andy Einhorn, neatly shifting from jazz-trio mode to deft simulations of orchestral color), the evening was dotted with familiar McDonald standards (including other singers’ one-time standards - Helen Morgan’s “Bill,’’ Barbra Streisand’s “Hurry, It’s Lovely Up Here,’’ Betty Hutton’s “Can’t Stop Talking’’). Such songs, though, are also opportunities for reconsideration. Even her most inescapable hit, Jason Robert Brown’s love-or-money tale “Stars and the Moon’’ (included, she related, due to a Twitter request), has grown more sophisticated in its storytelling: long, spacious vowels for the narrator’s confident suitors, more clipped, conversational diction revealing the narrator’s own insecurity.
Her singing was an opportunity to notice both her own evolution - the tone has grown darker and deeper - and, at least indirectly, the evolution of musical theater itself. Broadway shows of late have been engaged in an arms race of belting, the athletic, laser-bright sound of most pop and R&B singing. McDonald can belt with the best of them (Harburg and Arlen’s “Ain’t It the Truth’’ rang with attitude), but the core of her sound (and the reserve of her vocal power) is a more classical technique, the traditional, legit music theater style, sustained notes that blossom into complexity more than accelerate toward impact.
So it was telling that the bulk of her new repertoire wasn’t new at all: Irving Berlin’s “Moonshine Lullaby,’’ Frank Churchill and Ned Washington’s “Baby Mine’’ (from “Dumbo’’), Gus Kahn and Walter Donaldson’s 1920s hit “My Buddy.’’ In that, or in a slowed-up, blues-shaded version of Rodgers and Hammerstein’s “It Might as Well Be Spring,’’ she brought out both the cheer and the lingering melancholy. McDonald, more and more, seems most at home in the suspended equilibrium so well cultivated by Broadway in its golden age, lightly dancing along the line separating a joyous heart from a broken one.