It was a rather chilly evening last night at Wolf Trap, but the National Symphony under guest conductor Julius Rudel often played as if it were a dog day of August.

Not that there weren't moments of inspiration in a program that was as diverse as it was interesting: Kurt Weill's suite from his "Three Penny Opera," Gustav Mahler's "Ruckert Lieder" and Brahams' sturdy but sweaty warhorse -- the Symphony in C Minor, Opus 68.

Perhaps the orchestra's lack of inspiration stemmed from the sparse attendance for this concert at Wolf Trap. A good deal of the house was empty.

Nevertheless, baritone Richard Stilwell sang Mahler's "Ruckert Songs" with great conviction and ease of expression.

Stilwell's voice is certainly light and flexible enough to provide the widest range of Mahlerian rhetoric. Indeed, there were moments in his performance such as the opening of "Um Mitternacht" ("At Midnight") where his noble declamation eclipsed even that of Fischer-Dieskau in the same repertoire.

Yet, from the orchestra -- which played far too loudly under Rudel -- the magic of the musical effect was often missed. There was little feeling from the orchestra of a musical partnership, little sense of making music together with the soloist, little coalescence of a musical experience.

A small wind orchestra opened the concert with very bright and sprightly playing in the "Three Penny Opera" suite. Appropriately this music is meant to be played loudly and coarsely. The band, plus such exotic instruments as banjo and guitar caught Weill's sleazy, slippery Weimar Republic-cabaret idiom perfectly. The Brahams symphony finished out the concert in a solid but unimaginative and routine reading under Rudel.