My audio rack is bright, will sand fill help?

Symposium under everything on the rack will improve the sound very much.

By all means fill it with sand along with an air bladder platform such as the Siesmic Sink along with some good isolation footers under both preamps.Just my two cents.

Placing the relatively low cost VibraBlock Constrained Layer Damper from Machina Dynamica on each horizontal shelf surface can often give relief from brightness and stridency.
I notice that back in 2003 Stehno commented on the need to decide how best to control vibration and resonance along with other worthwhile suggestions.
Perhaps your new rack is going to need so much augmenting and adjusting that Chayro is on the right track suggesting this particular item is best removed from your system.

I have a VPI turntable stand for my Clearaudio Innovation. I use a 3' maple platform as a top supported with cones. The cones screw into the bottom of the platform. My other stands are maple, but for my turntable I want something more solid that is not affected by vibration.

My stand is filled with sand and it helps quite a bit. Use high grade childrens play sand or that fine gray colored sand. Don't use regular sand.

Henry, what happened to your lab table?
david