Mezzo Jane Irwin, an Edinburgh Festival regular, made her San Francisco Symphony debut tonight in a fetching 300-year-old novelty. Handel's youthful cantata "O Numi eterni (La Lucrezia)" is not only a premiere for the West Coast, it must be a blue-moon special most anywhere (with the notable exception of the recent Lorraine Hunt Lieberson recording). "La Lucrezia," with its after-the-fact lament of the rape by Sextus Tarquin, is dramatically compact, Lucrezia's despair and rage communicated with economy of text and a broad, varied sweep of music. It was an excellent showcase for Irwin's ample talent. She has a warm, agile voice, with a velvety, clear tone. Handling difficult dynamic changes smoothly, transparently, Irwin is notable in not flaunting that ability, focusing on the music and the text... or, at least, the former. Her diction is not on par with the excellence of her secure phrasing, bright high notes. The conductor was Bernard Labadie, making yet another strong impression. His direction of Handel ("Lucrezia" and the "Water Music") was impeccable, he conducted the Bach Orchestral Suite No. 4 with "Handelian" liveliness and excitement. Janos Gereben/SF www.sfcv.org [log in to unmask]