A few of you appear to use the Auralex Gramma on your bass cabs. I was wondering how safe are they with a 1 x 15" Ampeg and the 4 x 10" Ampeg stacked on top. They state 300 lb loading, mine with both cabs and SVTCL is 240lbs approx so ok there. My worry is would the four rubber feet on the bottom cab "walk " off the Gramma hence tilting the stack and hey presto the whole lot tumbles to the ground !! I have had boominess problems at certain stage / floor venues and the Gramma sounds a good low cost solution. Any thoughts or experiences of toppling off the pad ??