Possibly the springy Gyrodeck suspension and your self-described springy floor are not made for each other. In addition, no disrespect to the Mitchell, but your system is worthy of a turntable upgrade. You might consider the purchase of an unsuspended turntable which you can then pair with a high quality isolation shelf, like a Vibraplane or Minus K. (You don't want to pair a suspended tt with a second suspension.) This is worth considering if wall mounting is impractical. Remember too that wall mounting is not a panacea; strong structural vibrations will be transmitted into a wall mount, too. You might ask an architect to recommend a suitable wall in your home that is relatively isolated from structure-borne forces. In addition, FWIW, I have had good luck with Adona rack systems. At least they used to be reasonable in cost for very high quality; I don't know where they fit in the cost continuum as of today. Adding the mass of a heavy rack might help with your footfall problem, or it might not.