nasaman
Make sure upstairs the speakers are de-coupled from the floor (no spikes), or it will become a soundboard for the bass, and ruin it.
If you can use a heavy plinth (eg: cement path slabs) under each speaker and then use 4 of these Sorbothane pad between the speaker and the plinth, 4 are good for 800lbs
https://www.ebay.com/itm/4-LARGE-SORBOTHANE-DISC-CIRCLE-FEET-PAD-2-5x0-5in-64x12mm-SILENT-PC-AMP-FIRM-70D/372429364953?epid=1031478471&hash=item56b6851ed9:g:O04AAOxycmBS70F6
Cheers George