Is it bad to stack your equipment

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.

If I had a $12K pre and some $20K sources, I wouldn't want to damage them either.
But at $900. sale price for my Adcom pre, and the under $1K prices of my other stuff... I am NOT WORRIED about the small ring markings on the tops (from rubber feet)
I DO keep my HOT HOT HOT amp, (a Forte 4a) away from the other stuff.. And my Audio Research PH-2 is at the top with extra spacing.
So my current rack is:
four shelf with sand in the metal frame and glass shelves dampened with rubber.
Bottom Shelf:
lower: Monster signature 7000 conditioner
upper: Sony 5 disc CD changer CDP9ES (to play for my pets all day while I am gone)
second from bottom:
Sony SCD777ES all by itself only because it is a top loader.
third from bottom:
lower: Adcom 700 DA converter on a cork mat
upper: on extra sorbothane footers Adcom Preamp
fourth from bottom:
lower: another Sony, 5 disc a SC? 333ES
upper: on extra feet: Audio Research PH-2
top glass plate covering rack has a lamp
My turntables are on other furniture.
And I just do not know where to put the Audio Research PH-1 I have too. (now it just sits under a table with one of the TT on it

If you're able to do easy woodwork consider building a diy Salamander clone rack. They easy to build if you're handy at all. The beauty though is that you can design it anyway you need and the shelves are always adjustable as equipment changes. Also they're very strong.

What Nrchy said above is a good reason to avoid stacking. Also the better you can get rid of the heat the more reliable your electronics will be assuming you keep them for years which many of us don't.

The answer is a resounding yes. Not just from a sonic stand point but heat is a silicon killer. There are multiple threads on heat and what it does to equipment or to leave it on or not to leave it on that you can research.

Michael