In a suite of noontime concerts, Andris Nelsons leads full-length Beethoven symphonies, complemented by chamber works of a presumably adventuous stripe. Some of these may pass for cutting-edge in part just because they are recent. Others—Schoenberg’s Phantasy Op. 47 (1949), Debussy’s Sonata for flute, viola and harp (1915)—are vintage yet retain the shock of the new. —M.G.