Classical music's spring brings festivals and much more Spring is, as always, a season for festivals. The big one in Los Angeles this year is the ongoing celebration of the centenary of Benjamin Britten's birth, initiated by Los Angeles Opera. The Los Angeles Philharmonic's weeklong Brooklyn Festival in April is an investigation into how the New York City borough has become a hot spot for young composers. But while festivals take up a lot of the oxygen on the performing arts calendars, there is much else: Christian Wolff As a teen in the early 1950s, Wolff was taken under John Cage's wing and soon became a prominent member of Cage's New York School. So the composer and his music were inevitably included in many of the celebrations of the Cage centenary last year. But REDCAT is now devoting two evenings looking at the 78-year-old's influence on younger composers. An eloquent classics scholar who taught both Euripides and music composition at Dartmouth for many years, Wolff's music can be indeterminate, requiring inventive strategies from musicians. REDCAT, April 22 and 23. $10-$20. http://www.redcat.org Jennifer Koh Not only did the American violinist prove a sensation starring in the revival of Philip Glass and Robert Wilson's "Einstein on the Beach" last year, she began the multi-year "Bach and Beyond" project, which mixes Bach's solo sonatas and partitas with 20th and 21st century solo pieces. She's now touring Part 2, which intersperses Bach's first sonata and partita with Bartók and the gutsy contemporary American composer Phil Kline, who has a liking for boomboxes and other forms of vintage technology. Hahn Hall, Santa Barbara, 7 p.m. April 24. $10-$32. artsandlectures.sa.ucsb.edu Jephtha Handel's last oratorio is both a deeply spiritual work written at the end of the composer's life as he was going blind and a startlingly modern one that, as the great Handel scholar Winton Dean notes, points "an accusing finger at the dark impenetrability of the government of the universe." Few dare to perform such painfully and meaningfully penetrating music. The Handel and Haydn Society of Boston - led by a devoted Handelian, Harry Christophers - takes important chances by taking this important masterpiece on tour. Walt Disney Concert Hall, 8 p.m. April 30. $54.50 to $109. http://www.laphil.com Pacific Symphony: Ellington The classical music establishment has long accorded Duke Ellington lip service, hailing him as one of America's most important composers. But he is rarely accorded the favor of regularly being played by organizations outside of the pop and jazz world. For the Pacific Symphony's annual American Composer's Festival, the Duke is finally the subject. Composer and saxophonist Daniel Schnyder, trombonist David Taylor, pianist Kenny Drew Jr. and the Duke Ellington Orchestra join the Pacific Symphony for the program. Renée and Henry Segerstrom Concert Hall, Costa Mesa, 8 p.m. May 16-18 and 3 p.m. May 19. $25-$185. http://www.pacificsymphony.org The Marriage of Figaro Given that so many major building designs are decided by competition, architects are required to be a competitive lot. But they can also be collegial. At Frank Gehry's invitation, French architect Jean Nouvel will design the sets for the Los Angeles Philharmonic's production of Mozart's "The Marriage of Figaro" in Gehry's Walt Disney Concert Hall. Gustavo Dudamel will be conducting and Christopher Alden handling the staging of this second of three Mozart operas being presented by the L.A. Phil. Azzedine Alaia will provider the costumes; the cast includes Christopher Maltman and Dorothea Röschmann. May 17, 23 and 25; 2 p.m. May 19. http://www.laphil.comhttp://www.laphil.com