I did so with Totem Sttafs. I think it's important to note that Totem's provision for loading is different than Von Schweikert's. Loading in Totem's is strictly for purpose of lowering the center of gravity, whereas VS's is for resonance control. I sent an inquiry about mass loading to Totem when I bought my Sttafs. You may want to do the same for the Forests, but I assume the response will be largely the same. They told me that the Speakers are tuned and optimized with no loading present. They recommend 5-10 lbs of loading only. I used lead shot, which IMO is much beter than sand. I've used sand in speaker stands and it can be a little messy, and I just have something against putting "dirt" in my expensive new speakers ;-)