Last Saturday marked the centenary of Hugo Wolf's death, and as part of its on-going retrospective of the composer's output, the Wigmore Hall gave us a rare opportunity to hear the Spanisches Liederbuch, arguably Wolf's most ambitious work, certainly his most daunting for performers and audiences alike.

Setting German translations of 45 Spanish poems, the Song Book examines religious experience and worldly love, as a group of "spiritual songs", dealing with the mystery of Christ's incarnation and the self-lacerating nature of human guilt, forms an austere prelude to a lengthy, bittersweet exploration of the vagaries of sexuality.

The singers were Christine Schäfer and Matthias Goerne, cultish artists both, though it was apparent that Wolf's Song Book exposes flaws in Goerne's methodology. His voice, of velvet and grit, is astonishing, though his brooding, expressionistic approach proves limiting here. In the spiritual songs, he can be remarkable, opening the work with a hushed, fervent rendition of Nun bin ich dein then contemplating the wanderings of the Holy Family in Nun wandre Maria with genuine wonderment. Once Wolf plunges into erotic territory, however, you become aware of a certain absence of wit and an inability to lighten the tone. Sometimes he blusters, fracturing Wolf's carefully delineated vocal lines.

Schäfer, rather surprisingly, is more impressive. She has moved into heavier, more dramatic territory of late, her silky voice acquiring a touch of metal in the process. In the spiritual songs, she plays the Magdalene and contemplates Christ's wounds with disturbing rapture. In the later songs, she trades indiscretions with the audience, letting us into a world of erotic secrets with indiscreet knowingness. This is great Lieder singing.

As always in Wolf, the pianist carries equal weight with the singers. Eric Schneider is sometimes roused to being over-emphatic by Goerne's fierceness, although elsewhere he exposes the subtlety of Wolf's writing with great beauty and restraint.