What If Wall Shelf Isn't Option For My Turntable?

Hi Everyone,

My turntable has always worked fine resting on a thick piece of plywood situated inside one of those 4-level metal shelf furniture gizmos.

I've changed to a much more powerful integrated amp, and my Vandersteens are VIBRATING when at normal listening levels - they look like somebody shivering out in the cold.

My domestic situation dictates that the turntable be close to the Vandys - something like 18 inches away from the left speaker, and maybe another 18 inches above in the air.

I also cannot install a wall shelf.

Is there anything that can be done to eliminate this feedback problem, barring going back to the old integrated?

I've read about suggestions of sorbothane, cutting a piece of granite, vibrapods, and whatever else, but I have no idea where to begin or what to try.

Any help at all is greatly appreciated - thank you!