Fans of the Los Angeles Philharmonic have been suggesting for some time that the traditional list of the "big five" American orchestras (Boston, Chicago, Cleveland, New York and Philadelphia, in alphabetical order) should be enlarged to a "big six," with Los Angeles rounding out the half-dozen. Such weighty decisions should not be made on the basis of one performance heard during a tour, but the orchestra certainly sounded impressive Saturday night in the Kennedy Center Concert Hall with Carlo Maria Giulini conducting.

The chief merit of the performance was high energy, from the hammered-out chords that opened Verdi's "La Forza del Destino" Overture to the hammered-out chords that concluded Beethoven's Fifth Symphony (the only performance it had in Washington last week). Giulini is a striking figure on the podium -- tall and angular, rather like the old pictures of Paganini. His gestures are clear, simple and vigorous, and the interpretations tend to come out that way, too. If extra credit is allowed for energy, to compensate for occasional imperfections in the ensemble sound, the orchestra from Los Angeles was actually more interesting on Saturday night than the orchestras from Philadelphia and Cleveland in their last appearances here. The simple fact is that Giulini made it easier to stay awake than Eugene Ormandy or Erich Leinsdorf did.

Perhaps we should give credit for imaginative programming, too -- in which case five points may be deducted for the Beethoven but 10 should be added for the centerpiece of the concert: the East Coast premiere of Ezra Laderman's Fourth Symphony, a very significant work by a Washington composer. The applause for this music was enthusiastic and prolonged -- much more than one usually hears at the introduction of a new orchestral piece. The lion's share of the credit for this enthusiasm must go to the composer, who is a master of orchestral sound and uses it eloquently in lyric and dramatic statements. But the performance was also compelling -- somewhat better than the world premiere that was broadcast from Los Angeles last season.

Interest of this kind is not what people usually measure, however, when they are assessing the relative greatness of musicians -- perhaps regrettably. The Los Angeles Philharmonic is exciting but it is not always smooth; it lacks the burnished tone of the big five, their variety of nuance in dynamics and phrasing, and above all, the feeling of effortless ease with which they toss off the trickiest passages. If these are the elements of greatness, the greatness of the big five remains without serious challenge.

The highlight of the evening was the eloquent and beautifully crafted Laderman Symphony, which can best be understood as a sort of debate and reconciliation between styles: romantic and modernistic, tonal and atonal. Laderman bases each of the work's three movements on ambiguities and polarities of thematic material, reinforced by similar diversities in the music's sonic and emotional textures. The first movement becomes rather tense about these differences of opinion, which are introduced by a very large brass choir; the second sublimates its tensions in a nonsectarian commitment to pure lyricism, and the finale rejoices boisterously in the discovery that tonal and atonal style can coexist harmoniously in a single piece of music. The most impressive achievement is the way these tensions are resolved without making either attitude a winner over the other; instead, the music moves to a higher level of perception where both styles can be seen as aspects of a larger reality -- music itself.