King, on electric guitar, also will join the Relache ensemble in Frederic Rzewski's Coming Together. American Holly Near's Hay Una Mujer Desaparecida, dealing with the disappearances of women following the overthrow of Salvador Allende's government in Chile in 1973, will be sung by Barbara Noska. The Chilean coup also figures in Australian composer Vincent Plush's On Shooting Stars for six instrumentalists.
Poet Henry Braun and other activists will open the concert with a brief poetry reading that includes We Are 5,000 by Victor Jara, the late Chilean folk singer and composer.
Relache at Mandell Theater, 33d and Chestnut Streets, at 8 p.m. tomorrow. Tickets: $10, $7 for students. Phone: 574-8246.
VLADIMIR ASHKENAZY/LYNN HARRELL. The noted Russian pianist and American cellist, both residents of England, have been teaming up quite a bit for recitals this season. Sunday afternoon for the All Star-Forum, the duo offers substantive, thought-provoking works from the repertory that - while not overtly political - contain convictions that cannot be regarded as solely musical. The program: Shostakovich's Sonata in D minor (Op. 40), Beethoven's Sonata in D major (Op. 102, No. 2) and Brahms' Sonata in F major (Op. 99).
Ashkenazy/Harrell at the Academy of Music, Broad and Locust Streets, at 3 p.m. Sunday. Tickets: $10.50-$26. Phone: 893-1930.
VERDI "REQUIEM." Any assemblage of forces gathered to render Verdi's non- operatic masterpiece is worthy of attention. Sunday, three local choral groups, four professional soloists and a professional orchestra will perform the heroic score under the baton of Steven Sametz at the Packer Memorial Church at Lehigh University in Bethlehem, Pa.
Sametz, an associate professor of music at Lehigh, has assembled a promising roster of soloists: soprano Jeannette Thompson, mezzo-soprano Meredith Parsons, tenor Paul Spencer Adkins and bass Mark Doss. The chorus comes from the combined ranks of the Lehigh Choir, the Choral Union and Concord Chamber Singers.
Verdi Requiem at Packer Memorial Church, Lehigh University, Bethlehem, Pa., at 3 p.m. Sunday. Tickets: $3, $6. Phone: 758-3178.
KRONOS. Of all the musical offerings this weekend, perhaps the most fulfilling will be that of the Kronos Quartet, at the University Museum at 3 p.m. Sunday. This first-rate contemporary ensemble is planning to play a number of jazz arrangements along with its classical entries, and you can find more information about the concert in "High notes" on Page 32.