A work of dark, searching grandeur, Prokofiev’s Fourth Symphony gathers sumptuous themes from his ballet music, revised in the postwar shadow of Stalin’s Russia. Britten’s Violin Concerto, a searing response to the Spanish Civil War, features James Ehnes, “a flawless technician and a serious, ever-perceptive musician” (The Guardian). Providing contrast is Debussy’s dreamy and sensuous prelude.