SATURDAY NIGHT in the Terrace Theater, most of the audience's attention will be rightly focused on tenor Michael Hume, a singer best known internationally for his performances as the Celebrant in Leonard Bernstein's "Mass." But the audience should spare some attention for guitarist David Starobin, who will be appearing in the relatively low-profile role of accompanist.

Starobin is not only a distinctive and proficient performer on the guitar; he is also proprietor of Bridge Records, one of America's more interesting small companies. Both interests blend harmoniously in his new Bridge recording, "A Song from the East." Judging by this record, it might be worthwhile to invite Starobin back to give a show of his own in the Terrace.

One of the problems that still beset classical guitarists is a shortage of a first-class repertoire. "A Song from the East" may help by opening an area relatively unexplored by American guitarists: guitar music of Eastern Europe. Except for Fernando Sor's "Souvenir de Russie" for guitar duo, which uses Russian folk melodies, all the music in "A Song from the East" is by Russian and Hungarian composers. Much of it involves the guitar with other instruments, and some is of startling quality -- notably "Hungarian Children's Songs" by Rezso

Suga'r and "The Little Predicament," by Gyo rgy Kurta'g for the intriguing combination of piccolo, guitar and trombone. Beautifully performed and recorded, "A Song from the East" is an eye opener for guitar lovers.

DAVID STAROBIN --

"A Song from the East" (Bridge BCD 9004). Appearing Saturday at the Terrace Theater.