The speaker (ELAC F6.2) has a footprint of 11" x 8" and weighs 44 pounds and I'm afraid it might tip over causing damage. It will be standing on thick carpet so vibrations transmitted to the floor should be minimal.
One idea that struck me to stabilize the speaker is at about 38" from the floor (i.e. 6" from the top of the speaker) attach to the back of the speaker, two hooks, each one about 1" from the side, and then on the wall, find a stud or other hard point, and at about the same 38" height, screw a strip of wood about 2"x 1" x 10" to the stud, parallel to the floor, with hooks on both ends, then use a cord (or wire) to attach the hooks so that even if the speaker tips a bit, it will be tethered to the wall and cannot fall over.
This has the advantage of not tying the speaker to a particular spot on the floor, and also of allowing rapid removal just by removing the cord or wire.
The above description assumes a wood frame house. In a concrete wall house, one would just drill holes in the wall, insert plastic plugs, then hooks.