The Saint Louis Symphony, an orchestra of considerable depth under the baton of Leonard Slatkin, joined forces yesterday with pianist Emanuel Ax for something of a musical Super Bowl.

Two of the three works performed in the Kennedy Center's Concert Hall--Beethoven's Piano Concerto No. 4 and Prokofiev's Symphony No. 5--reflected giants of composition at the zenith of their powers. Beethoven's overture to "The Creatures of Prometheus"--though not by any means tossed off--did the job of getting the audience mentally and emotionally prepared.

Ax and the orchestra gave the concerto a delicately balanced, unhurried and often arresting reading. Because the piano and orchestra always talk to, rather than past, each other, the work has been likened to chamber music. Yesterday's performance did right by Beethoven's te te-a -te te, with Ax plumbing musical depths with the easy authority of a virtuoso, and using his sustaining pedal for an unusually lush and dreamy sound.

The conversation between piano and orchestra might have profited from more argument here and there. In the stark second movement, which has a well-tempered piano calming its agitated partner, the tension seemed to evaporate a bit too early--which is a quibble about a beautifully brought-off performance.

Slatkin won from the orchestra, especially the percussion section, a crisp and detailed Prokofiev--and a performance that also conveyed the work's sweep and majesty. From grave to lighthearted to explosive--as in the mighty blast that ended the Adagio--it was music-making of which even a Russian could be proud.