I have just ordered 3 Giai feet to try under the turntable. Stunning that some of the isolation units for speakers cost more than some speakers I've owned. I'm sure the law of diminishing returns applies to these.
Sorry if I wasn't clear, it sure seems you got the wrong message. There is no such thing as diminishing returns, not if you do it right. If you compare for example going from dirt cheap Nobsound to Gaia then yes totally diminishing returns. You pay a small fortune for only slightly better, if that. Mostly what you get is convenience and appearance. Performance is a wash.
Going from Gaia to Townshend, now you pay a lot more but you also get a lot more. So no diminishing returns there. Actually the last time I heard this was moving Pendragon XL to Podiums, it was like a whole system upgrade. Brandon was saying it was like the whole room was treated.
That is why I abhor the diminishing returns canard, it is simply not there other than in the imagination. In reality you are as likely to find accelerating returns. If for example you had some expensive cones or spikes that cost more than $30/set of four then going to Nobsound will be better for less. So it can go both ways making diminishing returns more something comforting to say than anything connected with reality.
You can find out real easy, simply order a set of Nobsound and compare. It will take a bit of effort, they work a lot better after a little trial and error to get the number of springs just right for the load. Once you do that though I think you will find they come real close for a lot less. Then if you do Pods, they are not just a little better than Nobsound, but a lot.
Podiums are a big chunk of the cost of my Moabs. But they elevate them to Ulf level performance. So it is all question of adjusting to the fact the components themselves are not what it's all about, but what you put the component on is equally as important.