– [Ms. Andsnes] bringing clarity, rhythmic élan and a touch of quirky playfulness to this demanding, audacious yet often humorous work. At the end of the 32nd variation, a formidable fugue, in which Beethoven’s music builds to a dramatic climax and leads into a short, elusive cadenza, Ms. Andsnes instead plays a five-minute piece by the Norwegian composer Lars Petter Hagen: “Diabelli Cadenza.” It’s written for piano and EBow, a hand-held resonator which prolongs sounds from the piano strings in softly eerie ways that suggest electronic music. From Mr. Hagen’s haunting cadenza, Ms. Andsnes segues into Beethoven’s final variation, a lilting, ingeniously ornate minuet, played beautifully. (Anthony Tommasini/New York Times)