Don't take that document on AVS as the Bible for Audyssey. Another user put that togethor from the common questions that come up, it is not set in stone.
Most people do not have a sealed room, I don't either and have 3 subs. Prior to calibrating with Audyssey, I just turn the subs on one by one while the others are off and calibrate them (in my case to 70dB), then run Audyssey. After the first seat scan, you can go ahead and calculate and see what the receiver trim level was set for the sub, if it is to low you can raise the trim knobs on the sub and rerun things.
