First, a complaint: why couldn't we, in 1991 and 1992, have the kind of sound that Sony could give Perahia or Decca could give Radu Lupu? Not that it's terrible, and Opp. 90 and 101 are a bit better than Op. 111 in this regard, but there was better sound to be had, and these performances deserve it. To a relatively uninformed listener like myself, Beethoven in these late sonatas seems to be reinventing the piano sonata as he goes along. In the Op. 90, I was thinking of anticipations of Schubert, especially in the second (and final) movement, but in the later two, he has gone beyond that into weirder regions that make even Schumann and Brahms sound conservative. The middle two movements of Op. 101 are riveting, and they stand oddly in sequence, although they contain their inner surprises too. You're always being kept slightly off balance, but the material is so engaging that your ear is led along. As for the Op.111, it does seem indeed a kind of terminus: where does one go with the piano after this? Both movements have a very varied character, and if the first (once you get into the allegro part, seems full of odd hesitations that alternate with something like brashness, the long second movement, that starts as if it's going to be a slightly unusual theme-and-variations (because the arietta theme is unusual) turns into something much weirder and more wonderful, moving into expressive regions where no music up to that time had come close to. Kovacevich plays it all wonderfully -- he is attuned to the wildness of the imagination here, though I doubt that there can be any "definitive" version of material as inventive as this. On to Brendel and Arrau!