Turntable Platforms - Low mass? High mass? Why?

Thanks Nsgarch, that approach does make sense.

Currently I have a Rega P25 sitting on a spiked Ikea Lack table - no mechanical diode as nsgarch calls out. I have been told that this is a good setup for this table. Would a Michell Gyrodeck work just as well on this end table? A Teres? Basis?

I guess I forgot to include spikes in the "mechanical diode" category. The Rega already has a "squishy" suspension right? So you're done!

The Rega philosophy is a light and rigid shelf or platform.Following this I had square piece of acrylic cut to size.Under the turntable you could have vibrapods under each foot.With a Rega P25 you have a 5 vibrapod at the back,a 2 at the next heaviest spot on the left and finally a normal vibrapod on the right where there is not too much weight.This sits on top of the acrylic shelf about 3/4 inch thick cut to size.You put some form of metal spiked feet under the shelf the same as those for speakers is o.k.The vibrapods were worked out after long testing and I can vouch it is effective on a Rega P2 although the original idea was worked out with a P25 and mentioned in the vinyl asylum and Stereophile.

That sounds like the way to go. How does it perform?

It cleans up the low-end quite noticeably and enhances detail.The vibrapods help the Rega feet drain away vibration as they are supposed to and the rigidity and decoupling effect of the shelf aids this also.