What's with this schematic?! It looks to me like the outputs are shorted directly to ground, and I see no connection from the speaker to the OPS! I don't believe that this schematic could be accurate. It's for the QSC 1700.
http://schematic.narod.ru/Files/Audio/semi/QSC/1700.jpg
http://schematic.narod.ru/Files/Audio/semi/QSC/1700.jpg