It's hard to miss German composer Wolfgang Rihm. He has an enormous head. There it is, bulging from his giant frame, a big, friendly grin slapped onto it while he wanders around the Barbican on his celebratory day, none of it going to waste. Listen to his prolifically combustible music, the million and one ideas hurtling about with the energy of a school playground and the intensity of a burning sun, and you soon realise that all that cranial space is probably quite necessary.