It sounds like the amp may be going into protection mode for some reason. I drove older Studio 60's with a 7500 without incident, but I was in a medium-sized space (maybe 3000 ft^3) and I don't know how we are defining "loud." There could be a wiring issue causing the unit to go into protection mode, although it would be unlikely for such an issue to only arise at high listening levels. Have you contacted Outlaw Support yet?