Advice on stacking equipment

Be careful as besides the isolation aspects, you're also putting a weight on top of a piece of equipment which often has as obvious audible effect (which may improve or deteriorate your system's performance).

I use hockey pucks between units when I stack

I stack my Innersound preamp and phone stage (they are both slim and light and exact sizes). Roger Sanders said they were designed to be stacked (he used to own Innersound-the electronics are made by Coda). I had them stacked for years but recenlty (3 months or so ago) I placed symposium fat pads between them (I always had them under the lower component). It did make a very nice change in sound (more detail, less phono noise, wider phone soundstage, seems to have tightened up phono base and widened soundstage on all sources). I wouldn't stack anything over a CD player. I have had some CD players, in the past, stop working due to weight issues on the player. I do have my squeezebox on top of my Benchmark (SB is very light) and have had nice improvement since I put squeezebox on a symposium svelt shelf and vibrapod disc under SB. My suggestion is perhaps ok to stack light gear but use isolation devices.

Besides the mentioned issues: Your equipment(digital OR analog) is emitting interference that will be absorbed by other gear(especially if stacked), and will affect your music signal. Digital circuits are really good at generating interference, as are the power supplies/transformers in any kind of gear. (http://www.peprollc.com/about/technology/threats/) I've always used Texas Instruments' TI Shield, over and under my individual components, to block any RFI/EMI. See page 14 of this catalog: (http://www.percyaudio.com/Catalog.pdf) The Stillpoints Suppression Cloth looks interesting too, but- I've not tried it.