From your pic it looks like hardwood, IOW a floating floor, so how are tighting up the joists of the subfloor going to help? There will still be some "spring" in the floor.
Even with mass loading, there will still be some bounce. The floor needs to be damped, with the addition of isolation footers under the component and if possible, isolation under the shelf.
Also IME, do not put any iso feet under the rack; it is likely to affect the performance of your TT. I'll bet your TT is very happy being on a heavy stand touching the floor.
Even with mass loading, there will still be some bounce. The floor needs to be damped, with the addition of isolation footers under the component and if possible, isolation under the shelf.
Also IME, do not put any iso feet under the rack; it is likely to affect the performance of your TT. I'll bet your TT is very happy being on a heavy stand touching the floor.