Canadian flutist Robert Aitken and American pianist Richard Goode, playing last night in Maryland University's Tawes Theater, gave new and welcome meaning to the unguarded border that separates their two countries. Both supreme masters of their instruments, they met onequal ground in musicianship, technique and style.

Aitken's tone is a reminder of the Silver Aria from the opera "The Ballad of Baby Doe," in which the heroine sings that gold is all very well but silver is like the beauty of the moon. Not seeking the huge gold sound of Rampal, the Canadian musician produces the widest variety of tone, all of it filled with expressive shading. From a Bach sonata he turned to Roussel's celebration of legendary flutists such as Pan and Krishna, making his instrument a thing of vivid textures.

In his own Plainsong for solo flute, Aitken combined technical virtuosity with novel effects, all of it to highly musical ends.

It is unusual to hear a pianist of Goode's stature collaborating with one of the world's top flutists. The second half of the evening opened with Goode playing Schuman's "Humoreske," which matched in its poetic beauty the Schubert Variations on "Trockne Blumen" with which the two artists closed the first half. In both works, the essence of the romantic era was recalled in an elegance of phrasing that was the embodiment of style.

Both artists showed their awareness of the cumulative power of the music they played. Thus the familiar Prokofiev Sonata, Op. 94, that closed the concert moved insuperbly sustained legatos into the dazzling brilliance of the scherzo, in which the articulation of both instruments was beautifully synchronized. It has taken far too long for Robert Aitken to reach our concert halls. The University of Maryland summer series has again brought Washington a fine artist who should be brought back at the earliest opportunity.