There’s no other symphony like Gustav Mahler’s Eighth. The piece got its nickname, the “Symphony of a Thousand,” at its 1910 premiere in Munich, which featured 1,030 performers, including 858 singers, 171 instrumentalists and the composer himself on the podium. Although a thousand musicians aren’t normally used these days (300 to 500 is more typical), it’s still a demanding and expensive undertaking,…