John Romeri during Mass on Aug. 8, 2010, at the Cathedral Basilica of St. Louis (RNS/St. Louis Post-Dispatch/Erik M. Lunsford) The head of liturgical music for the Philadelphia archdiocese, who was also to play a key role orchestrating the huge outdoor Mass concluding Pope Francis' trip to the U.S. in September, is resigning his post over long-standing differences with Archbishop Charles Chaput. John Romeri, who has headed the archdiocesan liturgical music office for five years, said he will resign effective June 30 because "there are simply irreconcilable differences" with Chaput over the role and style of music at Mass. Romeri...