Concertgoers got seven pianists for the price of one last night at the University of Maryland Piano Festival. When Russian virtuoso Youri Egorov became ill in Amsterdam a few days ago, festival director Eugene Istomin decided to substitute seven pianists who had come to serve as jurors in the competition.

The result, last night, was a concert by Edith Picht-Axenfeld, Lory Wallfisch, Bruno Canino, Joseph Kalichstein, Constance Keene, Jean-Bernard Pommier and James Tocco, a once-in-a-lifetime array of pianistic talent.

The concert certainly established the right of this panel of judges to sift the outstanding piano talents of the younger generation and find the top prize winners. It would be odious to do such sifting among the judges; they are all players of high achievement and each of them is unique. But if one moment in the evening is to be singled out as its high point, it would be the extraordinary, brilliantly hard-edged interpretation of Debussy's "Feux d'Artifice" by Canino. At another extreme of expression, Keene's phrasing in Chopin's Ballade in G minor had exactly the right kind of waywardness, and she made the "Three Chinese Pieces" of her late husband Abram Chasins sound fresh and new. Kalichstein matched the music's changing moods impressively in Mendelssohn's Fantasie in F-sharp minor.

The others formed partnerships: Picht-Axenfeld and Wallfisch for four-hand music by Beethoven and Mozart; Pommier and Tocco for Debussy's fascinating two-piano arrangement of six canonic etudes by Schumann. It was an evening of great variety, fine playing and a lot of unjustly neglected repertoire.