Thanks for those replies.

I already know the customaudiodesigns website from a year ago I did some improvements in my flat but I decided not to do all that contsruction work, e.g. building a floating floor with various products, building a new wall, etc. Its all very very expensive when you do the costings.

I first saw the Auralex Gramma platforms on that site and I ended up buying a pair from an American supplier, for use under my floorstanders. I believe they are pretty effective in stopping vibration going into the floor. Believe it or not that concrete floor does vibrate ( its not thick ). I think it let me get away with floorstanders.

My main interest in this thread is really with in room influences on misbehaving sound. e.g. boomy bass, reflections off wall behind sofa, etc etc. I'm about to buy serious speakers so I want to aid room acoustics now if I can.

Is it just trial and error with traps and pads if you don't have access to an analyst or can't afford one?