I just put together two new racks and have my 452 sitting on the bottom level directly on the cross members of the rack. The amp feet are about a 1/4" off the ground. I feel ignorant for even asking, but I was curious if this was generally a bad idea? I'm still contemplating removing the cross sections and letting it sit on the floor or attaching Stillpoints or something, which is a whole other topic. This isn't my picture but this is generally what the rack looks like although mine is set up in a more narrow fashion.
