Heavy difficult to move speakers- how do you deal?

Make sure to cyro treat the casters and have them engineered for directionality. 

Wait! There might just be a new market opening up.

Tweaks that Roll, or Moving Tweaks. Caster Snake Oil. 

I really like what @lak said.  Most of mine have a place to screw in already.  But I am little weird about them sitting on casters from a purist standpoint.

use 3 of these

2" casters, need 3" height for dual layers of ball bearings

surface mounted top plate, use screws or two 1" x 2" ez pass strips

1" wide ezypass strips

2" x 4" clear, cut to fit

THERE ARE VERY SLIPPERY  SLIDERS OUT THERE - I HAVE 6  OF THESE UNDER MY DUNLAY 6 SPEAKERS (520LBS) AND I CAN MOVE THEM SORT OF ENOUGH TO GET TO THE CONNECTORS - THESE WOULD WORK GREAT UNDER LIGHTER SPEAKERS

I have never seen 520 pound speakers. That’s nearly 3 tons of speakers