By Michael Roddy BERLIN, Jan 23 (Reuters) - In his youth, theoretical chemist Joachim Sauer found the music of Richard Wagner "bombastic". All that changed when he was in his early 20s with a chance encounter with Wagner's 'Siegfried'. Now the annual Wagner summer festival in Bayreuth is one of the few occasions when the media-shy Sauer is seen in public with his wife, German Chancellor Angela Merkel.