Riccardo Muti, who is the principal guest conductor of the Philadelphia Orchestra and Eugene Ormandy's successor, led the Philadelphians in a big, romantic program at the Kennedy Center last night.

If one were to take the closing moments of the Brahms Second Symphony as indicative of Muti's musical inclinations, one might write him off as a sensationalist, looking to pure power and brass for his effects. If, on the otther hand, one were to consider the extraordinary instrumental balance in the first movement, one might be moved to declare him a genius. He stripped away the glop of Brahms' thickness, revealing flute lines that rarely see the light of day, baroquish antiphony between strings and winds, and other delights.

Clearly he is a conductor who has assimilated the virtues of both the contemporary school of clarity and reason, and the more emotionally laden school of his predecessors.

Pianist Alicia de Larrocha was the soloist in the Beethoven Concerto No. 3, and seemed not up to her usual splendor. The music moved in short phrases, overly careful and not comfortably integrated, as if pianist and conductor were trying very hard not to step on each other's toes.

The opening Ligeti "Ramifications" for string orchestra undulated rhythmically and tonally, the halves of the orchestra, turned a quarter tone apart, weaving a sensual texture of provocative sounds. It is a spellbinding piece.