Thanks everyone for the info. I didn't see where there was an Auralex pad in the size I needed. However, I have been informed of the Great Gamma which I have been told may stick out at most 6", but that is better then having vibrating floors. Again, thanks for the input. That's what makes these forums so good, all the experience in one location.
By the way, has anyone ever bought a Great Gamma and put a table saw to it to narrow down the portion sticking out?