This is simply a matter of reducing the floor boundary reinforcement of the bass frequencies. Getting it off the floor reduces the reinforcement of these frequencies by 3db and tends to make it less boomy sounding. It also may have the effect of having the speaker more in-line with the ear at the seated position.
Note: Use an open type of stand if you are going to do this. Using a flat front closed stand will not have the effect, as it will help to re-couple the floor boundary to the sub, and thus add back in the boundary reinforcement.
Note: Use an open type of stand if you are going to do this. Using a flat front closed stand will not have the effect, as it will help to re-couple the floor boundary to the sub, and thus add back in the boundary reinforcement.