Robert Levin; Fortepiano Christopher Hogwood - The Academy of Ancient Music. Grand pianist and musicologist Robert Levin joins forces with Christopher Hogwood in this performance of Mozart's piano concerto # 15 in B flat major, K.450. The splendid performance gives us a real idea as to how the forte piano sounded in Mozart's time with the original pitch to boot ! Mozart described this concerto to his father when writing of K.450 and the 16th concerto in D; " "I consider them both to be concertos which make one sweat; but the B flat one beats the one in D for difficulty."