Peter Orth plays the piano beautifully. There is constant evidence of careful thought behind all that he does, and he offers a wide range of dynamic levels, frequently making use of a lovely, quiet tone.

However, in the Terrace Theater of the Kennedy Center on Saturday afternoon, in two Schumann Novellettes, the G Major Sonata of Schubert and the Liszt Sonata, Orth left his listeners with some troubling results. The Schubert sonata is of almost insufferable length -- only a few interpretive geniuses have suceeded in giving life to its overlong reaches. Orth moved through all the notes without a single problem -- his technique is more than enough for any demands. But the music was seldom probed, seldom made vivid.

In a defferent way, the Liszt was as unsatisfactory. Generally speaking, its large moments came off well. But this work, more than any other, depends upon the pianist's understanding of the interstices, those myriad pages that carry its message in richly embroidered filigree. Nowhere did Orth reveal the epochal character of the sonata. It was too studied, and the fugue much too calculated. This is music in which a certain degree of "go-for-broke" is essential. Orth made lovely sounds, but they did not add up to enough. Perhaps he should expand his repertoire from Saturday's excessively narrow range.