Try filling metal stands with 'wood' cat litter from tesco. It's low mass, high damping, rather than high mass found in sand & shot, which stores energy & ruins the sound ( no bass extension, false thump to the bass, lack of image depth) Being wood it dumps energy qiuckly, rather than storing it & creates a natural, livelier, more musical sound with a more tuneful bass & clearer, cleaner mids & highs. I was quite suprised at the improvement to the sound after replacing the sand with this & it's cheap!!! Give it a go, tell me what you think.