"The sonatas of Mozart are unique," said Artur Schnabel. "They are too easy for children, and too difficult for artists." It was performances like Mikhail Pletnev's that inspired Schabel's maxim. Pletnev's technique is awe-inspiring, and the smooth, room-sized sound he gets out of a grand piano promise wonderful things as one begins listening to the disc. But there's a certain refusal to fool with the music, a Zen detachment perhaps, that's necessary for a really good Mozart performance, and Pletnev does too much tinkering. His chief mannerism is a slowing of the tempo, nearly dramatic enough to be called a pause, at sectional divisions in the music -- not only at repeats, but even between thematic groups. The sly subtlety of Mozart's approaches to musical junction points is one of the great joys of his music, and it does not require the performer to hammer the point home. Pletnev does better with the Beethovenian Piano Sonata in C minor, K. 457, than with the three earlier sonatas on the disc, and his approach is also better suited to the slow movements of each of the four works, with their more expressive musical language. The exotic "Rondo alla Turca" at the end of the Piano Sonata in A major, K. 331, is likewise a pleasure. But the blithe spirit of Mozart's keyboard music emerges only intermittently here.