I mass loaded my old pair of ProAc EBS out of necessity, as they are just the right height to support a one-inch piece of plywood used as a large display table beneath the windows in our bedroom. The table holds a heavy 28" brass Buddhist statue and a collection of fluorescent rocks at one end and displays some of my tungsten element collection and more rocks at the other. Having the ProAcs on the floor eliminates any chance of imaging, of course, and the bass is now unfortunately exaggerated, but the speakers still fill the room with beautiful music, and the subwoofer I had intended to add to the system ten years ago sits unopened in its box. The added mass improved the sound of the ProAcs overall (with the noted exception of the additional bass boost), and they admirably support the makeshift table. :-)
