Among this generation of piano virtuosos, Jeremy Denk might be the biggest intellectual. That's not just because he writes for the New Yorker and maintains a prickly-smart blog: Evidence of his genius is also alive in this unlikely but perfect pairing of Ligeti's piano etudes and Beethoven's final piano sonata -- the one where the moody composer-in-winter hit a mood-shift and happened upon the future of ragtime. Denk doesn't try to "solve" for this jagged pivot; he just revels in it. Beethoven nuts will want to hear this version, and perhaps give Ligeti's witty, bold miniatures a new hearing.