Monitor users, isolation?

You want it rigidly coupled to a high mass stand. The more the speaker is allowed to move about the worse it will sound. A flimsy stand or soft material between speaker and stand is not good. A stand like a Sound Anchor will make a HUGE difference in how a speaker sounds.

http://www.soundanchors.com/page53.html

I'm using 3 posted Sound Anchor stands so a shelf between stand and speaker wouldn't work.

Blue-tack between the speaker bottom and the steel stand filled with sand on spikes . Each stand weighs @ 35lbs.