Well studying the thread further I am not sure how to explain, flyboy909 experienced a similar problem in a room about half the size (4300 rather than 7300 cu ft) and also during time of moderate playback volume; the only real commonality was not reference volume but rather HT sound effects (given my experience and commonsense logic presumably LFEs). I give up!!! Nah, never, I love a mystery! ;\)

"If you try to turn toward it, you go against it."