Filling speaker Stands?

Another option is cast steel shot if not willing to take precautions. [ dust mask, gloves although the one time exposure level is so low as to be inconsequential  ] Its density it about 75% of lead. Sand is barely 15%

Rice is probably not a good idea as it is organic and not very dense. Rice may damp, but is unlikely to eliminate tube resonance. It's density is half of sand.

Sorbothane has improved everything where used. One must get the right size and duro. As far as marking, who cares about the bottom of the speaker? Sorbothane creates a unit of the stand and loudspeaker. Other materials may not.

My X wife left me and all of her Valium. I used that in the stands to mellow out the sound. Worked as you might have imagined it would. 

soundsrealaudio.....been there. If I had enough valium to fill speaker stands my problem would be much larger than pursuing better sound. By the way...are valium pills smaller that small grain rice?I just want constructive advice.
Good luck with your problems.

Anytime you have a cavity you should have it filled.

Thought I would revive this thread with the weirdest experience I've had in this hobby. I had Atacama Nexus stands which were filled to the brim with Atabites. I experimented with 50% filled and then 75% filled which sounded better before settling on 100% filled because my bookshelf speakers are quite heavy (Dynaudio Contour 20). The Nexus stands were pretty wobbly so my thinking was that the more weight the better since it would be more stable. To be honest there was no difference in sound quality between 75% and 100% filled. I just filled it because there were spare atabites and I didn't want the stand to wobble. I enjoyed this combination (C20 on Nexus stands) for a little under a year, the sound was open, the bass was deep and rich.

Fast forward to 5 days ago and I copped a new pair Dynaudio Stand 6 stands as there was a discount to good to pass up with the local AD. Upon transferring the atabites from the Nexus stands to the new Dyn Stand 6 I realized that there weren't enough atabites because it was filled until halfway or 50% only and not the recommended 75%. The Dyn Stand 6 is more robust compared to the Atacama Nexus (its also 2 times the price which is why I didn't buy it in the first place (doh!)) and has a damping material sandwiched in between top and bottom plates and my first impressions were that it sounded okay at 50% filled but not as open sounding as the Atacama Nexus was with atabites filled to the brim.

So what was my solution? Buy more atabites! So I bought a tub and filled it up to the recommended 75% filled amount. Turned up the juice and my jaw dropped because it sounded horrible! Life was sucked out of the music, anxiety and worry washed over and I thought to myself what have I done? 

Did some quick research on overdamped stands and true enough someone from a Singapore hifi forum experienced the same thing with his Dyn stands and atabites. He ended up removing all of his atabites. 

The following day I removed half of the atabites and left about 1/4 filled in each stand and lo and behold, the C20's are singing again. They sound better than they ever were with the Nexus + 100% atabites filled combination.

The moral of this long and winding post is: what is recommended does not always translate to best results (granted Dynaudio website recommends filling up the stands to 75% with dry quartz sand and not atabites) and secondly, sometimes less is more. I hope this can help someone not make the same mistake as I did as he too will have a tub of inert silver pellets hidden under his couch.