I had a similar problem, my listening room has a beautiful maple floor with a thick Tibetan rug on it and the optimum place for the speakers is on rug. Spikes would have gone through the rug and ruined the floor. I tried using the spikes set on a piece of wood cut to the size of the speaker bases but just didn't feel I was getting everything from the speakers I could.
I went to a marble and granite supply house and found a scrap of green slate about two inches thick which yielded two bases an inch longer and wider than the plinths for the speakers. Rather than put the spikes onto the slate I decided to try the isolation route and bought rubber and cork isolation pads from a source here on audiogon.
The improvement was dramatic, better bass, much more open mid-range and treble. Total cost of the slate was $20 cut to size and the isolation pads were another $20. I used an orbital sander to smooth and slightly round the edges of the slate and the soft green color with the cherry finish of the speakers looks very trick.
I went to a marble and granite supply house and found a scrap of green slate about two inches thick which yielded two bases an inch longer and wider than the plinths for the speakers. Rather than put the spikes onto the slate I decided to try the isolation route and bought rubber and cork isolation pads from a source here on audiogon.
The improvement was dramatic, better bass, much more open mid-range and treble. Total cost of the slate was $20 cut to size and the isolation pads were another $20. I used an orbital sander to smooth and slightly round the edges of the slate and the soft green color with the cherry finish of the speakers looks very trick.