well i put the "bad" sub into the "good" box and no crack sound. so i then put the "good" sub into the "bad" box and i heard the sound again, so i put my isolation pad under the box and no sound. So I'm thinking the sound was coming from the cheap laminate flooring that the subwoofer sits on. But i can't use my isolation pad as the subs already block some of the projector screen. Is it ok if i have my left and right speakers infront of my subs? like have the subs firing into the back of the towers? the towers are front and down firing ports. I would leave some space between them just not sure if it will hurt the subs or towers. Im limited to where i can put these monster boxes. right now they lay down on their sides and under the screen but i feel like the sound like they are lacking, so i was thinking maybe corner load them but then thats putting them behind the towers.