Which support for underneath CD player?

Pend there are a thousand opinions on this issue: My own results with inner tubes were not good at all, but it won't hurt to try it. Good results were achieved with a Black Diamond shelf sitting on Vibrapods. Cones are then placed under the CDP in between the BD shelf; BD #4 cones are presently installed, but sometimes the BD #3's or even brass Audio Point cones with saucers are better, depending upon the downline setup in use at the time. Similar setup is under power amp , tuner & preamp, but these are better without cones in my rig (yours will be different of course).
However I found that those glass doors are awful & it all sounds much better with them removed. This was true whether the doors were closed or left standing open

I have had excellent luck with the Machina Dynamica Nimbus isolation base which uses a Firestone air shock as the primary isolation device. The air shock is gravity loaded with 30# of dead weight and the pressure set at 28-30#. Based on my experience with the Arcici airhead, I think that Arcici's approach is rather simplistic and prone to variable results. I find it to be little better than an inner tube (which is exactly what the Arcici is-three or four tractor tire inner tubes in a nice box). If your decide to try this approach, experiment with inflation (less is often better than more) and with mass loading. If your cd player is light, try adding weight to get the total to 30# or more. Good luck.

I too have greatly benefitted by adding a Neuance shelf under my Theta Pearl. Basically it extended the strengths of the Pearl. Mine sits on the top shelf of my Target Beta rack, and Ken Lyon can custom make one to fit your rack.

try putting it on a maple chopping block. also try putting hockey pucs under it .

Audioquest sorbethane feet. Cheap, and you can hear the difference.