I’ve tried spikes, slip sheets, wheels. Some people believe in springs.
I put 3 wheels on my speakers.
they stay where I leave them, yet move easily enough to adjust toe-in if a friend is listening with me, roll completely out of the way when I need to get behind this or that.
normally forward for best listening, push back some when I need to put 2 leaves, or push back more when I put all 3 leaves in the dining room table for big holidays, parties
Current Speakers:
a. aside from everything else, the axels need to be tight or there will be wobble, no good. I use dual wheel furniture casters with flat top plate, swivel/roll/no wobble. they stay where I leave them, push enough they roll, but no wobble or inadvertent movement.
b. 3 wheels, not 4, for two reasons
1. more weight per wheel than if speaker weight is divided by 4.
2. always stable, no shims needed, no vibration
c. Anti-Tip blocks. two wheels in the front, 1 wheel centered in the back. then add blocks in both rear corners that do not reach the floor, but will hit the floor if/when the speaker tilts just a little.
see 9th photo of my speakers base and innards in my system photos here
in my case, the skirt is close to the floor in the back, preventing tilt. I put a 1-1/2" block above the front wheels to tilt my speakers back some. that aims the tweeter’s up to seated ear height, changes the angles of early wave reflections off floor and ceiling, and approximates ’time-alignment’ of faster traveling high frequencies.
see 1st photo. I have objects on both speakers, the 15" woofers can shake the joint, but there is no vibration, nothing moves on top, and that’s with no special internal bracing. Some of Donna’s favorite things on there. Meaning, the 15" woofers do not make a heavy speaker on wheels move by themselves.