How do you move a 650lbs Rack on Hardwood...

Don't put the masonite directly on the floor! Use heavy rosin type paper of a light moving pad.

My rack doesn't weight quite as much as yours, but it is still a couple hundred pounds, loaded. I do not use casters but points. I have the discs that the points go into and felt adhered to the bottom of the discs. These allow my whole rack to slide nicely on my wood floor, especially if you are sliding with the orientation of the wood (not grain, but how it is laid).

The plastic disks Sfar mentioned, also come with a heavy felt like material on their bottoms for movement over hard flooring. While masonite may be the ticket, plastic movers have proved invaluable to my wife and I.

It took three men and a boy to move a new very large door chest into our bedroom. They were lifting and lowering and angling it to go around a corner and beneath a door way. Later, my wife and I put it on the plastic disks, and slid it out of the room over carpet and ceramic tile with ease.

I suggested the disks to a buddy to move a machine lathe in the 600-800 lb. range. They worked quite nicely.

These may not be for your use, but we use them several times a year. In fact I just moved a piece of furniture with a 50” plasma on it – couldn’t have easily done it without those little guys.

A really simple and cheap solution: Put a couple of folded towels under the unit. It will slide easily over the floor and there will be no dents, scratches etc. I have 350 pound subwoofers that I have moved this way. I have no strength in my arms or upper body whatsoever, but this way I can move them myself.