I have a 120 year old house with a "suspended" wooden floor. I bought the EP350 sub. I haven't noticed any loosening of floorboards. I am building speaker isolation "sandboxes" for the EP350 and my M60's. Auralex has "MoPads" that reportedly do a great job at isolating the speakers. So, if your concerned, just isolate 'em, which in theory will improve their sound anyway...