Does your speakers have a threat to screw spikes into the feet? Often they do.
Mine have an 8 mm threat. I didn't want to damage my wooden floor. So I bought 8mm s/s (stainless steel bolts) (looks a little smarter than galvanised bolts), stuck a "Glass Skid Protector" (transparent rubber pad) on each and screwed it into the feet. To make it stick better, I glued it on with Superglue. I got get the "Glass Skid Protectors" from Game. You can even get s/s nuts to put on the screw so that it does turn to much. Hope you getting the picture.