I use Symposium Ultra platforms under a couple of different components and the Svelte shelves under my speakers. Like any vibration damping products, it is a matter of "tuning" so that more damping is not necessarily an improvement--it is possible to achieve a too dry and analytical sound with some components. I heard a demonstration conducted by a Symposium representative at a local shop where different Symposium platforms were placed under a CD player. The sound improved with the cheaper platforms, but, their most expensive platform turned out to be too much.
My speakers sit on the Svelte shelf without any kind of footers on the speaker so that almost the entire bottom of the speaker cabinet is in contact with the shelf. This maximizes the vibration damping of the cabinet (vibration is transferred to the shelf which has a foam core that dissipates the energy as heat). Because my speakers sit on carpet over a suspended wood floor, this arrangement reduces the amount of vibration transferred to the floor (which would otherwise sort of act like a sounding board). Again, as a matter of tuning, this works positively for me, but, in another setup, this might be too much damping.
My speakers sit on the Svelte shelf without any kind of footers on the speaker so that almost the entire bottom of the speaker cabinet is in contact with the shelf. This maximizes the vibration damping of the cabinet (vibration is transferred to the shelf which has a foam core that dissipates the energy as heat). Because my speakers sit on carpet over a suspended wood floor, this arrangement reduces the amount of vibration transferred to the floor (which would otherwise sort of act like a sounding board). Again, as a matter of tuning, this works positively for me, but, in another setup, this might be too much damping.