What isolation feet under your amp with great result?

3/4"MDF and casters.  My amps weight 85Lbs each.  The great results are not hearing me groan or pull a muscle while cleaning.
 

All my components rest on Machina Dynamica Springs. The science is sound, the result is amazing, and the price is right

@tweak1 , Geoff has been saying "mass on springs" for years, and after the past two months of trial and error I have ended up with springs under my heavy speakers and amps.  The spring stiffness (i.e., spring rate), load capacity, diameter, and height are all important considerations.  I have used heat shrink to damp the single springs and even that was a learning experience wrt the size and thickness of the heat shrink used and how those factors affect the performance of the spring, as well as the need to put a hole in the heat shrink to prevent an air lock.  The heat shrink also improves the look (pics on my system page) and prevents scratching on the bottom of your components or the tops of your rack shelves.  I also have a bunch of Herbie's products here (Giant Fat Dots and Gliders) and based on my experience so far I would have a hard time deciding whether springs or Herbie's footers sound better. 

I like the feet these guys are making,  Turntable Phonograph Vinyl Record Player lsolation Feet – Mnpctech

I have only used one isolation vibration product and that’s the EVP’s. I used these under my speakers. I placed them under the speakers for about a week a just let the music play. I then set aside several hours where I played music I was very family with and would play the music w the EVP’s then remove them and play the music over again. The EVP’s definitely have a positive affect on the sound. When I removed them it sounded as if the life was sucked out of the music. With them the music sounded cleaner(more transparency), more dynamic, just overall more musical. I still would like to experiment with more isolation systems bf making a purchase, EVP’s made me a believer that concept of controlling vibration and its affect on the music isn’t just selling snake oil.