My friend had a Bose micro-cube system with an outboard (Bose) subwoofer sitting on top of his antique wooden equipment cabinet. It was aesthetically pleasing and to give him credit, there just wasn't space for anything else in the room he chose for his system.
After going over to his place for about eight months, one day I decided to ask him a question: Do you want your system to sound better? Knowing what my investment in stereo gear was, his immediate reply was, Only if it doesn't cost me an arm and a leg! To which my immediate response was, How does six pennies sound?
He was MUCH happier with the way it sounded already, but when I turned and asked for the six pennies, he again became puzzled. Reaching in his pocket, he produced the coins.. So what's the plan?
The top of his antique cabinet was refinished many times and its surface was no longer flat. As a result, when we pushed the upper edge of either cube, you could see each of the two speakers rock ever so little if not only to the most gentle touch. After demonstrating this to him, I said, Here, you do it. Put three of the coins under each speaker, two in front and one in back making a triangular pattern. He did so and moved the cubes back onto the locations marked by the painter's tape.
Now listen again to what you had just played and tell me what you think. My friend looked at me as if I had a neon sign strapped to my forehead that said "weirdo" but played along with me anyway. Much to his total astonishment, he gasped. What happened? Why is it so much better, so much more detailed, so much wider and deeper?
Here is what I said, Your speakers, although tiny, are rocking just a little as the piston moves in and out. At one point, they will resonate ever so slightly on the surface and even cause a sometimes barely audible buzz. It is this minor movement we have eliminated. Your speakers still rock but now they rock quite a bit less.
I have done this trick to tens of my friend's systems each of which were (are) eternally grateful. If you have not done this to your system, do it now in the manner described above. If your speakers are sitting on top of a rug, screw three wood screws into the floor below and set the speakers on top of them (just a test; you can get better things to use later than these screws but just about everyone has six wood screws lying around somewhere).
Anyway, after scooting your speakers around to find the right position for them, put your speakers on top of the pennies or the screws and see what you hear.