Footers?

For mass loading, which does work great on digital gear IMO, try some DY remedies first. Take some plastic zip lock backs and load them with sand or kitty litter. Note the weight (you may want to make up a few of varying weights) and place them on top of the player. See how it sounds.

I have some VPI bricks and use them on top of my VAC amps and Lightspeed. My transports sits on top of my DAC so its mass loaded that way.

Then there is the HRS method. Take a look at their damping plates. Something else you could DIY with some 30 or 40 durometer rubber from McMaster.

You can have too much weight. Its an art not a science.