In the whole symphonic repertoire, it would be hard to find two works that contrast more dramatically than those played by the National Symphony Orchestra last night at the Kennedy Center: Mozart's Piano Concerto No. 24 in C Minor and Shostakovich's Symphony No. 10 in E Minor.

The orchestra that came out for Shostakovich after intermission looked approximately twice as large as the one that had played Mozart in the first half, even counting guest soloist Justus Frantz at the piano keyboard, and Shostakovich used his forces, particularly in the second movement, with a power and ferocity unimaginable to Mozart. This violent movement contains a portrait of Stalin, who had died a few months before the music was composed after endangering the composer's creative life for 40 years.

The Shostakovich symphony and the Mozart concerto are both deeply personal statements. Mozart is wistful and intensely expressive in a way seldom found in orchestral music before Beethoven. Shostakovich puts a sort of signature on his last two movements, using a four-note motif that represents his initials (D. Sch.) in a musical code. In this pensive, violent and, at last, quietly joyful music, the composer is saying: "This is mine; this is myself. My creative spirit has survived the brutal tyrant." It is good music for this time of crumbling walls, but it is good music for any time.

It is always a special event -- a tribute to friendship and a celebration of music itself -- when Mstislav Rostropovich conducts Shostakovich, and last night was no exception. The orchestra, superbly controlled, balanced power with delicacy as the music required. In Mozart, the orchestra deftly engaged in a dialogue with the soloist (particularly the woodwinds in the slow movement), but its ensemble playing could benefit from a bit more rehearsal. Frantz played smoothly and with a good sense of the music's expressive dimensions. His cadenzas (one using some ideas of Saint-Saens) were imaginative, well integrated into the concerto and stylistically appropriate.

Mozart and Shostakovich were also featured in a prelude chamber recital showcasing some of the orchestra's new players. William Wielgus, a new oboist, played beautifully in the Quartet in F, K. 370, with Paul Roby (new assistant principal in the second violin section), Yun-Jie Liu (a new violist) and cellist Steven A. Honigberg. Shostakovich's Eighth String Quartet, which contains the same "initials" motif, received a powerful performance from Charles Wetherbee (new principal second violinist), violinist Teri C. Lee, Roberto Diaz (new principal violist) and cellist James Lee. All these players have been hired since Rostropovich became the music director, and their performance helped to explain why the orchestra has improved so much in that time.