I am using a product like this under my Hsu sub:

Aurelex SubDude II.

https://www.bhphotovideo.com/c/product/969016-REG/auralex_subdude_ii_subwoofer_isolation.html?ap=y&smp=y&msclkid=cdd589d9277412c4410def41335905eb

Works well and definitely helps isolate the low frequencies. Highly recommend.

 Thanks, I will research it.

I suspect if your sub is vibrating you probably have it turned up way too much. Assuming you are talking audio and at volumes less than 100db then it should be filling in a thin band of low frequencies and well typically if you can hear it it is turned up way too high and is interfering with the overall audio spectrum.

When my subs were tuned in I could feel no vibration whatsoever with my hand on them.