Facing the unpalatable possibility of a return to financial instability (even as its artistic fortunes climb,) the Cincinnati Symphony is preparing to launch a major endowment drive, as well as a drive to remodel its concert hall in the city’s notorious Over-the-Rhine neighborhood. Music Hall is the largest orchestral concert hall in the U.S. – it seats more than 3,400 – and CSO officials have long contended it is far too large for a city of Cincinnati’s size. By comparison, most other major concert halls seat fewer than 2,500 concertgoers.