Susana Baca is a remarkable woman. Brought up in a coastal barrio near the Peruvian capital of Lima, she travelled across the country, learning the songs of the descendants of slaves.

She became the country's best-known performer of Afro-Peruvian songs, added favourites from South America, and won a place on the stages of the world. Now, for her new album Espiritu Vivo, she has mixed in a dash of the avant-garde, and material ranging from French chanson to Björk.

Does the new style work? Yes - but with limitations. She came on in a long white dress and shawl, and eased into a slinky 17th-century Peruvian song, Toro Mata. Then came the half-spoken Caracunde and a breathy ballad, La Noche y el Dia.

When Baca played the South Bank a year and a half ago, she was backed by just four musicians, two of them percussionists with Peruvian instruments. They are now part of an extended band that includes experimental jazz player John Medeski on keyboards. Together they added effects, solos and embellishments, as the new-style Baca demonstrated her expanded repertoire.

There were delicate, sad-edged ballads and a shift to French for Les Feuilles Mortes, in which she became a Peruvian Piaf; then came upbeat songs in which she took off her shoes, lifted her long skirt and danced elegantly. All classy stuff, and she deserved her standing ovation. But the spontaneity of the past was somehow missing. Her own band was capable of handling all her new musical interests; it was hard to see why the new additions were necessary.