Best Isolation Device for Speakers?

This thread is of great interest to me currently. I have recently placed my 5As on a piece of MDF over the carpet on a large second floor listening room over the garage. I did this to help me move them around for purposes of testing. What I discovered is that the speakers had much more life in them on the MDF. The highs were much clearer and the vocals more magical. After listening for a couple of weeks, I put them back on the carpet in exactly the same position and the life was sucked back out.
I had previously believed that the speakers were best off coupled to the floor, and the 5As have cones which I assumed were coupling devices. Now I realize that for reasons I can't explain, the image is much better with a degree of isolation.
Let me also say that the cones may not have penetrated the thick carpet and pad very successfully.
Can anyone help here? Should I be considering a better isolation platform under the speakers? Or should I be cutting through the carpet to let the cones get to the subfloor? Can an of the Systrum technology help? I looked at their stands and I don't think they can mate to the botton of the 5A with its sub opening and grill.
Thanks for any help.

I am most interested in what is going on here. When the speakers are spiked onto the floor, this should create the best path for resonant energy to depart (good), and this should increase the energy input into the floor which drives the natural floor resonance (bad). Putting the speakers on MDF over the carpet should reduce both the good and bad effects above. This is the dilemma.

I can notice this dramatic improvement when listening to a female vocal with delicate symbols and piano in the background. So there are no heavy bass notes that might be shaking the speakers or the floor. Also, for what it is worth, I can easily feel the floor resonate around 30HZ when conducting SPL measurements. However, the I have adjusted the subs in the 5As and have a smooth response from 20 to 160 HZ within +or- 3DB.

Yesterday I bought some heavy cutting boards to try under the speakers in place of the MDF. I am just trying to confirm what I am hearing with another material. I would like to try the Systrum platforms, but it would seem to raise the speakers up too high for proper listening. With regard to hanging the speakers on wires, these 5As weigh 185 lbs. each!

I spoke to Richard Vandersteen at CES about this and he doesn't like putting the speakers on MDF because he felt they would not be stable enough (movement front to back that would distort the image). His answer was to strengthen the floor from underneath.

I'm still trying to figure out where to go next. Thanks for your ideas.

My listening room is in a formal living room with cathedral ceilings and a very strong WAF. I am just lucky to have it there at all! The decorator once came in and asked if I could push the speakers back into the corners. That got a lot of support from the other half. I am afraid hanging is out of the question or it would be my hanging!

Barry, thanks for such a good description of the USE in audio systems! So given this, can isolation platforms (designed to convert vibration into heat) that are most frequently applied to components and amps be applied to speakers? What are the pros and cons?