I have 4" thick maple stands that I use under my subwoofers. Under the maple I installed some 2" Star sound Audio brass points.
http://www.starsoundtechnologies.com/productsDetail.php?2.0AP-1--View-Details-for-Model-Numbers-14
ozzy
http://www.starsoundtechnologies.com/productsDetail.php?2.0AP-1--View-Details-for-Model-Numbers-14
ozzy