The Axiom port plugs have done a great job of mechanically decoupling my dual 125v4 from my living room hardwood floor. I tried Trevor's suggestion of carpet under the sub but that didn't get me all the way there.

I slid two of these on the back side beside each foot and one on the front between the two feet. That did the trick.

https://www.axiomaudio.com/port-plugs

Think I might try this just because.

Hi Blair. Good to see ya.