Also another point, you mentioned the screams seeming to go on forever and ever, any auto calibration will help tame peaks in the frequencies, but you are going to want to do a little bit to tame that physically as there's only so much that the auto calibrations can do. In fact, if it is a really echo-y room, that could hinder the auto calibration, too.
I would cover some of the hardwood floors with a rug or something directly in the line of the speakers. Bare walls, even pictures or decorations can break up the sound a bit. These are simple ideas if you don't want to put acoustic paneling into your room.