Your homemade tweaks?

Gel wrist rests like those used with computer keyboards make effective isolation pads and are fairly inexpensive.

1 1/4" copper couplings over the male, and female ends of upper end power cords - the only areas of most cords not shielded, Seems to reduce line noise and the system is quieter.

Lining my speaker cabinets with Dynamat (from auto parts stores) significfantly reduces cabinet resonances yielding improved clarity.

Replacing all driver steel screws with brass screws - noticeably improves clarity.

Elizabeth, great idea! Where for you find antistatic foam?

Cast off Corian counter top pieces from kitchen installers for amp or speaker platforms or on top of CD player to dampen resonance

Rubber vibration dampers used in industrial settings for equipment footers

Foam rubber playmats wrapped around large cardboard tubes for bass traps

Wheelbarrow tire inner tube in a homemade frame for an air cushion platform

Boos Block cutting boards are the best maple platforms out there at much less cost. Just put any feet you want on them or use blue tak?

To buy antistatic foam: Online electronics, or computer parts supplies sell small squares of antistatic foam. Radio Shack here in the USA have it. For my original DAC foam, I bought the Radio Shack foam. Got about 6 of them.
Recenty I wanted to redo some, and found by Google, places that sell antistatic foam in bigger sizes. A 'blue' foam is also available, but do not use that. The dark grey/black foam in 1/4 to 3/8 inch thick is best. I found a place selling 40 inch by 40 inch sheets @ 3/8 inch thick and I bought two of them. (enough to last me a lifetime!!) It took two months for them to send them!!! (I had given up! and then there they were!) So for the two sheets it was about $60.00 US.
When you stuff the top, connect all the plastic encased bundles of foam together with a bare wire, and cut up the foam so it really fills in the space. Just make certain the plastic you use to insulate the electrical stuff from the foam will not melt! most DACs do not get hot enough to melt plastic anyway.
For under the main circuit board, You will have to take it out put down the foam under with a thin cardboard shield (Pepsi Cola/Coke multi can packs have a perfect thickness cardboard) to protect the underside of the board (I do NOT recomment using plastic under the circuit board, as the bottom of the circuit board is full of pointed bits of soldered stuff, which could pierce the plastic, if you used plastic). Taking the main board off then replacing it is not much of a problem with most DACs. (but a CD player it would be VERY difficult.. And I would not disassemble a CD player to put it under the boards. But on a CD player, you can place the foam to the sides and top of the insde case for a bit of the effect of cutting the internal RFI.
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So just Google "antistatic foam suppiers" or the like and find one that can sell you what you need. (some will only sell to other manufacturers, or only orders over $$. (I think that is why MY order took so long, They waited until they had a BIG order, and added mine little one in to it.)
Good luck!