Securing Monitors to a stand

I use some rubber foam mat that I got at Home Depot in a role to cushion the monitors and protect the bottom surface.  Think I found this in the carpet area.  

Then I use a black nylon strap about an inch wide with a sliding compresion buckle to strap them to the top of the stand.   Think I found this in the bungy cord area.  

The Velcro alternative sounds good also - though, it would stick to the finish of the speaker and be difficult to remove - if that matters.  The holding / bonding strength wouldn't be that crtical since gravity would be holding the monitor down.  Applying a 16 lb force from the side would be unlikely... if... your careful around them.

Also - I use a concrete patio block (16" square) as the base under the stands and spikes rest on the block - very stable and difficult to knock over - compared to sitting on carpet.

Weighing in...

There's 'turner's tape', a seriously sticky double-faced tape available at woodworker's stores, such as Klingspor.  1" w. typically, grey, leaves no residue, typically used to stick wood to lathe plates (albeit generously in that application).  If I want something to 'sit and stay' until I say 'move', that's my goto.

If you desire something more aggressive,  there's 3M's VHB tapes available from Uline.  You can pick widths and degrees of 'sticky', foam or film.  BUT...VHB's can Really Be Strong, to the point of permanence.  If you opt for a foam carrier, you can slice it apart with a razor blade and rub it off the surface with your fingers (it's a rubber based adhesive that'll 'roll up' like rubber contact cement...but won't be quite as quick to do so...your finger tips will complain about it....)

And there's always a dab of clear silicone adhesive.  Acts like the VHB, but can act like a rubber 'foot' if you let it set up awhile first...