Damping Top of CDP

I've used sand filled zip lock bags on top of my speakers with success. Also, just go to a gun shot and pick up a bag of lead. Another cheap tweak that will replace the feet on your player is to get the HVAC rubber/cork blocks. These are the same as what Mapleshade sells only for a lot lot less if you can find an HVAC dealer or supplier that has them.

An alternative is to try placing multiple smaller items on top of your Music Hall like lead shot filled Gumby action figures. If you pick something too heavy like that gi-mungous Golden Gate Bridge bolt Marco [Jax2] use to use it might over dampen the chassis and cause the sound to deaden. Using multiple smaller items allows you some adjustability. Just one Pokey might sound better than two Blockheads, or a Groov-Bee. Experiment!

I have used the Virmode.com "Virtual Mode De Bag!" successfully, and it only recently has been de-throned by the "Mini" Brilliant Pebbles from machinadynamica.com.
Both companies are quite independent-minded, and worth checking out for anyone who enjoys the joy of discovering a "tweak" that makes things sound better, not just different.
To get the full flavor of Virtual Mode's emphasis on being the most cost-effective source one must telephone for their full catalog.
Machina Dynamica is more into tweaks that border on the supernatural, and prices range from the most cost effective, up to the very most effective, regardless of price.
Don't forget the supporting structure/devices for your CDP box, which are available from Virtual Mode, Machina Dynamica, and many other sources, in a multitude of sizes, shapes, materials, and prices.
My little known "find" of a support product is Mi-Roller from Musical Industry at mihorn.com, which is one of the many competitors to the Aurios MIB (media isolation bearing), at a lower price point.
The choices are too numerous in the affordable price range to pick a single champion, but most seem to enhance the listening experience in one or more ways.

Get a Radio Shack project box.
They come in various sizes and fill them with pennies.
Not only does this provide the mass loading but the copper provides shielding.

I dampend my Arcam9 on the inside cover with a product called" BrownBread", this has dampening sticky side for attachment and aluminum on the other for heat absortion. it is a British prouduct and can be ordered from any dealer that sells any english produck like rega for instance, it cost me $26.00 Canadian, the 3M product sounds to me to be in the same vein.Good Luck Ernest.