Otherwise known as the East Coast Chamber Orchestra, this fast-rising conductorless ensemble comes to the budget-priced Peoples' Symphony Concerts series with a fascinating program: Geminiani's Variations on "La Folia," Janacek's Suite for String Orchestra, Ginastera's Concerto per corde and Shostakovich's Sinfonia (an arrangement of the composer's searing String Quartet No. 8).