The doyen of Austrian pianists, Rudolf Buchbinder, has a long relationship with Beethoven’s Diabelli Variations, and here he broadens the horizon with terrific results. In addition to Beethoven’s 33 variations on Diabelli’s perky little waltz, he includes eight further variations from the 52 written by Beethoven’s contemporaries—Hummel, Schubert, Liszt, and Mozart Jr. among them—each worth hearing. But of even more interest are the 11 by composers of today. Among them, Lera Auerbach’s, the longest, is full of foreboding. Brett Dean’s bursts with energy, Max Richter’s is deeply atmospheric, and Rodion Shchedrin’s is very witty. Tan Dun’s delivers crystalline beauty while Jörg Widmann’s is truly virtuosic.