Absolutely, I am sure a suspended deck would benefit from active isolation as well. But they would work pretty well on any rigid structure also. So the performance increase is likely to be marginal. Not so with non-suspended / non-decoupled decks.

I can demonstrate the effect in my system by letting out the air. It isnt subtle especially at high volume. As a number of people are lining up for a listen I wil get one of them to check it out and report back as a second opinion.

AK - in your opinion. I dont see you offering a better rationale or experience, or indeed any form of technical contribution. What you have presented is a "hunch". If the route I take contravenes mainstream wisdom then so be it.