True to its title, the St. Paul Chamber Orchestra provided both orchestral music and chamber music last night at the Kennedy Center to open its three-day visit to Washington. It also played something in between: chamber music with inflated instrumentation that shows the advantages and the disadvantages of orchestral music.

Mendelssohn's Octet and Samuel Barber's Adagio for Strings (originally composed for string quartet) were both performed with more than 20 string players participating--far more than the original scores call for and about half what we would hear from a full symphony orchestra. The effect was lovely, of course. This is a superb little orchestra, lithe in its phrasing and precise in its ensemble sound, and conductor Pinchas Zukerman paces and balances it well, whether he is standing with a baton (as he did in the Barber) or sitting in with his violin (as he did in the Mendelssohn).

The tone was excellent, although it lacked the lushness of the Philadelphia Orchestra or the National Symphony. The violins shimmered and the bass tone was rich. For the Kennedy Center Concert Hall, where chamber music can easily be dwarfed by the size of the auditorium, it was probably more effective than it would have been with only one player to a part. But there was also a loss; the feeling of free give-and-take that lies at the heart of chamber music was replaced by the sense of discipline appropriate for an orchestra. The intimacy that is one of the chief joys of chamber music evaporated, partly because of the number of players and partly because of the size of the hall.

The adaptation of these two pieces allowed the orchestra to include music of the 19th and 20th centuries in its program, and the performance had a beauty all its own, despite the compromises.

Where the sense of true chamber music emerged most clearly was in the dialogue between the soloists (Zukerman on violin and Yo-Yo Ma on cello) in Johann Christian Bach's Sinfonia Concertante in A, which opened the second half. Sometimes they played in close harmony, and sometimes they engaged in dialogue, but the best moments of all were the passages of imitation, where Zukerman would spin out a phrase on his violin and Ma would echo it precisely on the cello, with little adjustments in tone and phrasing that made it completely his own. The music was no more than charming, but the playing was exquisite, and fortunately neither of these great string players is afraid to include a bit of schmaltz in 18th-century music.

The evening concluded brilliantly with the familiar Gru tzmacher reconstruction of Boccherini's Cello Concerto in B-flat. Ma's solo playing was subtle, soulful, rich in tone and beautifully controlled, as this young artist's playing always is.