sid, that would make a difference in the bass your sub gives, but only if your sub is a bottom firing sub. If you sub fires from the side like most pc subs do, and home ones for that matter, then the difference wont be nearly as noticable. However if you take a look at a higher end sub maker like velodyne for instance, almost all of their subs have a built in piece of wood with about a 1" clearance under the subs.