Hope you are well. I think it had more to do with his room vibrations and squeeks dying down between notes. Sounds like you need a well dampened and nailed tight room to utilize that beasty. Friend of mine has two 16-46PC Plus in a home theater room with acoustic tiling and wall treatments, the whole nine yards. In that room they sound fantastic without vibrating the room structure, but they sure rumble your organs, eyeballs, popcorn, etc.... hehe. These are the 525 Watt versions with the aluminum Plus driver and different port design, and also incorporate a subsonic filter, which probably helps a lot with unwanted vibrations. I guess it is worth it to get the more expensive Plus model.
Looking at the frequency response graph the newer model has a ruler flat response from 16Hz to 100Hz, where the PCi model is tilted up in the lower frequencies and rolls off to around -5db down by 100Hz. Could make it boomy.