The platforms under the Isis and Osiris were done a good while ago so detailed findings have faded in the mists of time. I seem to recall similar improvements under the cd player and amp, although I logically started under the cd player.
But I was that pleased with the results i then started thinking about the Podiums under my speakers. I ummed and ahhed over them for a fair while , in part because I had tried some IsoAcoustics Gaia under my previous Rega RS10 speakers which were not a success. But fairly recently took the plunge on the Podiums and very glad I did.
I would say the podiums have by far the most impact , although the cumulative effect may have some bearing on it.
You can just buy the seismic pods individually to put underneath your equipment if wanted.
You can also buy them direct from Townshend's at a much better price than listed !