It is a suspended floor and you can feel it movingOk you need to decouple all the speakers from it, you’ll be amazed at the sound transformation you get.
Audio branded decouplers can get expensive.
Sorbothane diy discs one of the best vibration decoupling/absorbers there is, are a great de-coupler, you need get the hard graded ones for the heavy speakers, as they may squash out too much, I’ve wrapped them in cling warp to limit this.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=Sorbothane+discs&_saca...
Cheers George