Mo,
I've also encountered the same accustic problems while performing in a gymnasium. In my case, which was about three years ago, I was using a pair of Barbetta Sona 32C powered speakers. The walls were hard tiles, the floors were hardwood and the ceiling height must have been nearly 30 feet. Just like performing inside an empty barrel.
My solution was similar. I turned the speakers so they faced the wall behind me, which was a distance of about 18 feet. The sound distribution was outstanding, no one complained about the music being too loud when they were close to the speakers, and I was hearing exactly what the audience was hearing.
Unfortunately, every venue is different and requires different EQs, different speaker positions, different everything. If there were just one setting and setup for all venues life would surely be a lot easier.
Good subject,
Gary
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Travlin' Easy