When Victoria de los Angeles and Alicia de Larrocha walked onto the stage of the Kennedy Center Concert Hall yesterday afternoon, the applause opened up, increased, and continued until, for a moment, it seemed it might not stop at all.

But as the two great ladies from Barcelona made it clear that they had come to make music together, the applause finally died away, only to surge up again after each song. It was a concert in which a kind of musical unity was present to a degree rarely attained these days. There were many times when, as in match between Bjorn Borg and John McEnroe, you tried your best to see everything each performer was doing all the time.

Alicia de Larrocha has been the unchallenged monarch of Spanish piano music for decades. Yesterday, hearing her in familiar songs by Montsalvatge, Mompou and Obradors was to hear these songs as never before. The trice-repeated introduction in Mompou's Song of the Soul were as breath-talking as De los Angeles' eloquent traversal of the unaccompanied verses. The pianist in Montsalvatge's Negro Song was matched by the singer in his Cradle Song.

Earlier, in Schumann's cycle on Women's Love and Life, De Larrocha offered frequent reminders that her Schumann also has no superior among today's pianists. In these, De los Angeles had less spontaneity than at other times during the concert. The audience, which filled the hall and half the stage, shouted with delight at the close of the program.