“Going big took on a whole new meaning at the National Arts Centre Tuesday, where the Ottawa centre’s 57-member chamber orchestra revealed that it will perform two mammoth Mahler symphonies next season, including the so-called “Symphony of a Thousand.” Mahler’s first (“Titan”) and eighth symphonies are both on the bill for the first time next year, along with another large Germanic piece, Richard Strauss’s tone poem Don Juan.”