Truisms are as plentiful in the music world as elsewhere, particularly with regard to performers. The "it-takes-one-to-play-one" concept heads the list and never ceases to add a little heat to debates waged in behalf of or against artists who specialize in works by their fellow countrymen.

In the case of Walter Klien, an Austrian pianist renowned for his recordings of the complete solo piano works of Mozart, such reference dropping certainly rests on the "pro" side of his approach to the composer. A Mozartean's Mozartean, he excels in his seemingly effortless ability to present the music without ever reverting to extremes.

Klien's all-Mozart recital at the Kennedy Center Terrace Theater last night presented interpretations that were never stodgy or excessively precious, yet retained the bloom of a freshly composed piece.

Three sonatas and a like number of miniatures plumbed several emotional strata, without straying too far from the drawing room. The sparkling Sonata in G Major, (K. 283), displayed Klien's forthright manner and utterly fastidious phrasing; in the closing Sonata in A Minor, (K. 310) -- one of only two Mozart piano sonatas written in a minor key -- he conveyed the composer's tragic sense of loneliness via shifting dynamics and tempestuous crescendos.

The Sonata in A Major, (K. 331), with its strange arrangement of movements that resembles a suite, provided plenty of opportunity for Klien the colorist. He attended to the theme and variations, sprightly minuet and novel Turkish exotica in the allegretto, with gracefully drawn lines and buoyant tempos.