Is it bad to stack your equipment

I have tried the "Twelve Step Program For Incurable Stackers" ... and failed.
I stack. Usually only two at a time. But at times I have stacked as many as FOUR items up.
Rules:
Leave the hottest one on top
Leave the biggest and heaviest one on the bottom.
Leave the preamp in the middle (shelved or stacked).
Try to alternate stacking of items in use at the same time.
Don't let the power cord of the one above run right over the inputs ot outputs of the ones below.

Well all my equipnment is stacked. Has been for years. I have gotten into tube pre amps and am now having issues. I was at my dealer about a month ago and he hooked up my system and was a/b cd players for me. he had one in the rack and one on top of the pre. after I listened for a while and decided he took the one off the pre amp and said it woudl now sound better. Couldn't beleve it! just adding air around the componment mades a big difference in sound.

For solid state I never herd a big difference but for the stuff I have now wow wouldn't of beleved it.

Bgrazman is right. Stacking can negate the very purpose of clean/dirty boxes. Also consider that the likely hood of scratching componenets or leaving traces of rubber footings increases dramaticly. This can devalue your equipment for resale. Those racks serve a purpose.

If you invest significant dollars in components because you think it's a good thing if one wants great sound, how on earth could you, or anyone, contemplate stacking them like pancakes? Do the right thing ... buy or make your own rack to hold equipment that either cost significant dollars or that you value for their performance. Too, a good rack adds to the overall listening/aesthetic pleasure. These things really do matter, don't you think? In my case, the Sanus Euro-rack works/looks just fine! Not that expensive, actually, and easily adjustable to meet changing needs. Go for it!

There are many issues in play, but yes, it is bad to stack. Some pieces of gear are very sensetive to electrical fields, and some pieces of gear throw out a big electrical field.

Amplifiers can interfere with CDPs and pre-amps. Racks can be made cheaply (you get what you pay for though) but better racks (read: more expensive) do a better job of stabilizing and islolating/coupling gear.

Some people go to great lengths and costs to seperate gear, and the results are worth the effort IMO.