Turntable isolation platforms

I would go to your local granite countertop site and ask them to cut you a 1.5 to 2 inch thick piece large enough to place your table on. all the imaging greatly improves and feedback becomes a non issue.

For most stuff millercarbon's sandbox solution will work fine. It is just a mater of making it look good. There is only one problem I can think of and that is the floor. Concrete floors are perfect for Hi Fi rooms because they are so stiff and non resonant. Wood floors however are spring boards.
More mass = lower resonance frequency = more bounce. You can really give yourself a foot fall problem this way. I have seen tonearms go airborne. With a wood floor there are only two solutions I can think of. A wall shelf which was previously mentioned which works great as long as there are not little ones crashing into the wall or a well designed suspended turntable. 
The Isoacoustics platform should isolate you from that "rumble" you have noticed. It will not isolate you from foot falls. If you are on a concrete floor the Isoacoustics platform will be all you need. 
Going back to turntables, the SOTA is a brilliant design actually more so than the Basis or SME. All three tables have properly designed and tuned suspensions. You can jump up and down in front of all three and nothing will happen even if you have crappy floors. But with the SOTA the suspended platform is internalized so you can bump up against the plinth and nothing will happen. When  placing the tonearm I can use the plinth as a steady rest. You can not do this with the other turntables. I have both a SOTA and an SME. The reason I got the SME is that I wanted to use a Kuzma 4 point 14 and SOTA does not make a turntable you can mount this arm on. If they did I would have gotten it. The SME is a great turntable but the SOTA is nicer to use and the Macassar Ebony plinth is drop dead gorgeous. The SME is...industrial. 
Having a properly isolated turntable is just as, if not more important than getting the tonearm set up dead on. If you get one of the above turntables you do not have to spend money on a special stand or shelf. You could place any of these turntables on a collapsible card table and they would work fine.  

brotw71
Ok, had to look that up. Mass on spring looks effective for isolating turntables through other means. I’m more interested speaker and component vibration solutions that drain sources of vibration to the floor. Haven’t seen many spring solutions for those. I think springs just solve the floor moving up and down problem rather than lateral.

>>>>As I already pointed out, mass on spring iso system operate in both directions, up 🔝and down ⬇️ That’s why you have such devices as inverted pendulums, etc. That’s why everybody and his brother says go watch the Townshend YouTube video on speaker isolation. A video is worth a thousand words. The mass on spring system is used for all (rpt all) isolation applications, including tube and solid state electronics, turntables, speakers, etc. By the way, even cement slabs move up and down, 

I am using a Symposium Iso Segue under my Classic III and can't recommend it highly enough. My floor is suspended over a large crawl space and the Iso Segue really cleaned up the lower end.

@todd30312  

What is supporting the Segue?