I agree with those above that if you have a suspended floor, you may well benefit from some isolation between the speakers and the floor. I had that problem in a previous room in spades as the floor had a natural resonant frequency around 32hz. After many trials, I found that a combination of slate under the speakers and a post under the center of the floor (in the garage) worked best.
I obtained 2 - 7/8" thick pieces of black slate 18"x24". The slate was heavy and relatively smooth (much more so that the slate typically used in a yard environment), however, as long as you have 3 spikes the smoothness is not critical. These pieces cut and polished on one side with finished edges were about $300. I also obtained an oil which when wipped on turned the slate a rich and shiny black which really looks great. To finish these off, I put some 12"x12" self adhesive vinyl tiles from HD on the bottom of the slate cut to fit. This allows me to move the speakers around on the carpet much more easily than with the relatively course unpolished bottom side of the slate.
The heavy slate on carpet/pad gave the needed isolation while still providing stability. The floor resonance was dramatically reduced and the bass tightened up considerably. This same result may be possible with slabs of heavy wood or butcher block as well, and I will be curious to learn what you find out.
I obtained 2 - 7/8" thick pieces of black slate 18"x24". The slate was heavy and relatively smooth (much more so that the slate typically used in a yard environment), however, as long as you have 3 spikes the smoothness is not critical. These pieces cut and polished on one side with finished edges were about $300. I also obtained an oil which when wipped on turned the slate a rich and shiny black which really looks great. To finish these off, I put some 12"x12" self adhesive vinyl tiles from HD on the bottom of the slate cut to fit. This allows me to move the speakers around on the carpet much more easily than with the relatively course unpolished bottom side of the slate.
The heavy slate on carpet/pad gave the needed isolation while still providing stability. The floor resonance was dramatically reduced and the bass tightened up considerably. This same result may be possible with slabs of heavy wood or butcher block as well, and I will be curious to learn what you find out.