Further experimentation with speaker isolation and vibration control resulted in the laminate material now sandwiched between stand and base of speaker.
This works much more effectively than standing the stand and speaker on the laminate. I have used a tiny bit of blu tack between laminate and stand but not between speaker and laminate.
Stands are half filled with sand and spiked through to concrete floor with 6mm spikes.
Immediately there was a large improvement in definition and stability to the sound. It was almost as if the speaker cabinets previously vibrated in an uncontrolled manner and blurred the image of the music as it were. Now I am getting more focus on vocals and instruments. Spacial definition especially deep into the mix is improved and extends further. It is as if the whole sonic picture has been stabilised and cleaned up. Very impressed and will be keeping this tweek in situ permanently as it has had quite a profound effect.
Now here is the interesting bit. Over Christmas I was looking at one of my favourite sites Analogue Planet and Michael Fremer did a post on Wilson Audio speakers. He posted up a video tour of the Wilson factory including a chat with one of the Wilson techies and remarkably during the interview he had a piece of laminate material not too dissimilar to what I have used, slightly different construction but the same idea. They are looking and may well be using it in their speaker construction!?