I Recently scored a 67' Coliseum PA Head, it's not marked on the back where the--Speaker--Extension Speaker input jacks are. I looked at the schematic's, and it is confusing? Can't find anything on the Forum either. My 67'-68'? Sentura II is the same dilemma--no markings for Ohms. Does anyone know what the ohms are for either of these 2 Sunns? Thank You.