MDF Rack dampening question

Hello all,
I'm using a 4 shelf MDF rack that has hollow alum metal columns, and plastic looking (may be silicone) footers. Floor is porcelain tile. There's lots of empty space between the shelves.

I feel vibration on my equipment while listening to music and I'm wondering if there is anything I can do to help eliminate this (short of replacing the rack)

Some ideas I am kicking around are listed, wondering if you have tried and if it made any difference.

Fill hollow metal columns with sand
Changing footers to brass spikes
Dampening material under each shelf (Dynamat Extreme or another) which would also block EMF between shelves
Mounting each piece of equipment on butcher block w vibrapods (or similar)

Home Depot "natural play sand" They had another, much thinner, called leveling sand, but I was afraid of the mess.

Ordered Dynamat Extreme 10435 door kit ($50). Trying to increase the mass on each shelf to reduce vibrations, and also it should give some EMF shielding between components because it has an aluminum sheet.

We'll see what happens.
With your additional choice of materials you are now trapping more vibrations and .....over a longer period of time. Instead of allowing for and providing a path for vibrations to naturally migrate away fom your components you have provided a greater storage reservoir. Have you provided a way for self induced component vibrations or those that travel thru the air a method of retreat? Tom
Im not sure I understand. Am I going to get negative results by adding mass to the rack with sand in the steel tubes and dynamat to the shelves? Floor is concrete, sub is on vibrapods, so I believe most vibration felt on the shelf is via the sound waves over the air. Other than getting the shelves made out of birch or another material, what else can I do?
I just bought the Studiotech PS-3 with the optional high mass cone feet for my TV/tube system. It replaced a flimsy rack with glass shelving that was clearly not made for audio at all.

The HF-4 is similar but I went with the PS-3 because of the added bracing. Its very rigid and with the cone feet on my carpeted floor and a 80lb plasma on the top shelf it doesnt move at all. I can tell you it is a huge improvement sonically - the bass is tighter with more separation, the mids became more lush and the highs seem to have smoothed out a bit too. Now certainly, this isnt a high end rack, but it was a very noticable improvement in my system for not much money.

I have my CDP and tube preamp sitting on the middle shelf and my Power Plant Premier sitting on the bottom shelf. My amps sit on Timbernation maple stands with brass cones to each side of the rack. Im ordering up some Black Diamond Racing cones for further isolation on the 3 rack components but so far Im happy with it.