Turntable isolation

You could try isolating with AudioQuest sorbethane feet. Keep in mind that they most likely will solve or reduce the "thumping" problem but may also change the tonal quality. Another suggestion is Black Diamond racing cones and an isolation platform between the cones and the table feet.

In most homes/rooms, turntables are more stable on a low solid piece of furniture closer to the ground. This minimizes vibrations and effects.

Can you put the table on a separate low stand or table next to the taller component stand?

I keep all my components including table low to the ground on a rock solid oak wood coffee table (about 80 pounds weight). The table also sits on teh concrete house foundation which is thinly carpeted. Vibrations transmitted via the furniture is a total non issue.

A wall shelf as mentioned could be another option as mentioned. How well that works would be a function more of the room and wall construction and how rigid that is.

I do have a table in my second system sitting somewhat high up inside a tall and solidly constructed Ethan Allen audio cabinet (see my 2 Channel Family Room A/V System listing here on Agon). This system resides on teh second floor with typical modern wood joist based flooring found in most homes. This setup has less stability than the concrete foundation on the floor below. This works out OK in my case with the less finicky Dual table used there but is not as solid a setup overall. Yet it serves the purpose for that system.

They key is to have the table sit on the most rigid foundation overall as possible, however that might be best accomplished in your case.

SYMPOSIUM Ultra Best by far mas means nothing without proper isolation!!

Look to Gingko audio. Simple concept, but it really works wonders!