Thanks for those thoughts.
the flooring is wood decking set onto 10 inch floor trusses, ans suspended.
the proposed subs to be used do have their own (optional) iso footers installed
I do not listen regularly to extreme levels. once in a great while perhaps. now and then one needs to "Pour some sugar" on it, or twist the fun knob up with some aC DC " you shook me all night long;'. otherwise nope. usualy the fun button rests on just above conversational levels.
the flooring is not tops in class but doesn't seem to flex or allow exterior forces to infuse exteraneous reasonances from merely walking about.
FYI.... there will likely be no TT used in the signal chain at all.