I went through the same dilemma with my 3 kids. My solution was to use the blue putty that you typically use to mount posters on walls, both to hold the speaker on the top face of the speaker stand and also to secure the bottom of the speaker stand to the hardwood floor. That stuff sticks like glue and doesn't damage the vinyl on the speakers or the floor finish. If you've got carpet you'll need other options.

M22's, VP150, QS4's, HK 630, HSU VTF3-MKII