I can't tell you the right answer, but here are some things to think about:
1. temperature & air flow
2. vibration/physical isolation
3. ease of keeping cables well separated
(I ended up building my own flexy type rack when I ran out of room & didn't want to pay big bux).
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.
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.
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.
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.
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.
One big issue with stacking involves components with torroidal transformers inside. Those are the round donought things. Picture this and you'll understand:
A torroidal projects through the hole in its middle. Kind of like a javeline top and bottom through the hole, for quite a good distance actually. If the torroidal is lying flat, then anything stacked above or below it has this javeline like electro-magnetic projectile shooting through it.
Shielding helps, but doesn't necessarily get rid of all of it.
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.
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
Elizabeth, I bought my pets sony walkmans. Color me cheap.
Elizabeths problem is why I had to build my own...
Went from a 5 high to a double wide 4 high... (and still have my headphone amplifier elsewhere in the room).
(setup is different than the picture in my virtual system. TT is now on a timbernation platform & Bow is now on a gingko)
I built a "Salamander" clone rack for about 45. bucks from Home Depot stuff. That threaded rod does cost a few dollars!
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.
Thanks everyone. I guess I better shelf each componet on there own. Without a woodworking shop I am not so good a working with wood. I think I better spend the money on a nice rack or hire a carpenter to build one for me.
Thanks again for all your input !!
You can still get someone (carpenter, stoneworker, timbernation.com, somebody else) to make the shelves to your spec & assemble the rack yourself.
For the uprights, you would need only threaded rod (hardware store), bolts, washers, etc. This is the basis of the flexy rack & a number of commercial designs as well.
Best of luck,