As good as Sandrine Piau sounds in the studio, she was even better live at the Phillips Collection. (Sandrine Expilly/Naïve)

Sandrine Piau made her long overdue Washington debut on Sunday afternoon, and the Phillips Collection, celebrating its 75th anniversary season, got the glory. The French soprano’s excellent program of 19th-century songs, superbly accompanied by pianist Susan Manoff, was the latest sign of the ascendancy of the Phillips concert series, which has become one of the strongest in the city.

Manoff and Piau recorded many of these songs on their 2011 CD, “Après un rêve.” The qualities that set Piau’s voice apart on disc were, if anything, more pronounced live: clarity of intonation more than idiosyncratic color, lightness at the top more than force, unmannered elegance of diction more than fussy precision. Her rhythmic freedom, always shadowed adroitly by Manoff, helped her create the sense of poetry being recited in music, especially in impeccable sets of French songs by Fauré, Chausson, Debussy and Poulenc. The music of that last composer in particular, sung with a natural ease and wry subtlety, has become one of her calling cards.

In the German songs by Hugo Wolf and Richard Strauss, the transparent top range of Piau’s voice was beautifully suited to incarnate every sort of elf, naiad, night spirit, and lost waif possible. Manoff added a kaleidoscope of colors at the keyboard, ringing out a pedal bell tone in Chausson’s “Les heures” or trilling for the fluttering nightingales in Strauss’s “Ständchen.”

Both artists let their hair down a bit in three Britten folk-song arrangements, with Piau even sitting on the piano bench with Manoff for the middle song. During “I Wonder as I Wander,” Manoff held down the piano’s sustaining pedal, allowing the strings to resonate with a ghostly shimmer during the unaccompanied passages. With two encores, Debussy’s “Fantoches” and Poulenc’s “La reine de coeur,” Piau ended in her strongest repertory.

Downey is a freelance writer.