Is it OK to put casters on the bottom of speakers?

I have a relatively heavy pair of NHT 2.5i speakers that sound best when properly placed but are inconvenient to the rest of the houshold when not in use. Does anyone have experience putting locking casters on the bottom of their speakers. It would be nice to know how you did it without destroying the bottom of the cabinet.
I think it's a very good idea. Others will surely disagree. If I were going to do it, I would attach the castors to a separate base that is actually wider than the speakers for stability. Then I would simply screw the base to the bottom of the cabinets which should do minimal damage.
At the risk of castering aspersions please don't do this to your speakers.
I have a similar problem whereby my large speakers (Avantgarde Duos) have to be moved forward from the back wall every time I listen to music. The solution I settled on was furniture "Sliders" I placed under my speakers. They are 1/2 thick and round, come in various sizes and have a sticky side that is placed against the bottom of the piece of furniture. They are teflon coated and easily glide over all surfaces including carpet. I bought them at Home Depot-- very cheap. No drilling into the speaker or otherwise permanent damage is necesary. Enjoy listening.
Oh dear, you have a dilemma. Let us know how you solve it. The tradeoff between mobility and rigidity is a terrible one. Ideally you want to anchor your speakers as firmly as you can, while maintaining a high impdedance mismatch between them and the floor. Cones and spikes do this quite well but casters, even locked, don't. Totem speakers use a ball bearing foot ( called a "claw" ) which sounds better than IMHO it should. Maybe something like that would be a good compromise.