Pacifica Quartet May 10, 2004 By Joe Banno Libby Larsen's 1991 quartet "Schoenberg, Schenker and Schillinger" seeks to explore the 20th century's path away from melody. Its three movements variously treat Arnold Schoenberg's democratizing of the Western scale's 12 tones, Heinrich Schenker's elevation of chords over melody and Joseph Schillinger's experiments wtih rhythm-driven music. The work's success at the Pacifica Quartet's recital Friday at the Library of Congress owed as much to Larsen's jabbing, enigmatically shifting score as to the Pacifica's zeal and commanding technical finish--and even more to the musicians' way of making the piece sound like a strange and deeply involving human drama. Small wonder Larsen was beaming during her curtain call. The rest of the program represented composers of earlier generations pushing the string quartet to ape other forms. Haydn's "Lark" Quartet is very nearly a chamber-size concerto for the first violinist (benefiting here from Simin Ganatra's sweet-toned and terrifically poised playing in the "soloist" role). And while Mozart's Adagio and Fugue in C Minor translates Bachian keyboard counterpoint into elegantly turned chamber music, Mendelssohn's String Quartet in D, Op. 44, No. 1, keeps bursting at the seams to become a full-scale symphony. The Pacifica brought out the strong personalities in all these works, thanks to a set of musical gifts held in ideal balance: exuberance bounded by a natural feeling for classical architecture, scrupulous ensemble enlivened by spontaneous-sounding phrasing, and clean vibrancy of tone working hand-in-hand with interpretive warmth and immediacy. (c) 2004 The Washington Post Company