Need help with stereo cabinet design.

For fans look at W. W Granger catalog, they have ones for every possible use. If it were me I would use something like the Star Sound rack that I use. It uses mainly open steel shelves with the components mounted on cones coupled by discs. Gives the best isolation I have has by far and you can build an enclosure with doors to hold it. There are other good racks available. I think this would give you better sound and the cost would probably be comparable to a custom built cabinet. With any custom cabinet , no matter the care taken, you never know how it will sound. Years ago Martin Colloms had a custom built cabinet made, even placing it on a large marble slab to add mass and so it could slide on carpet. It weighed several hundred pounds but was not a success despite his best efforts. If you use a rack you will at least know what you are going to get and many of them are very attractive.

jgialco is SOOOO right. Listen to him totally!

Just thread refrigerant tubing in the isolation draining sloted maple or I might add Myrtle shelves. Put the compressor far away in a different structure if you can. The compressor draws a bazillion amps so keep it well clear of the audio component's dedicated lines and have it on a 240 volt outlet of it's own. You will need a very quiet tuned port to evacuate the air evenly . a simple bulbous portable Oreck type house hold vacuum cleaner should be kept in the basement rember to get a very long special extension tube with splitters and nozzles for each compartment.

I would build a small closet between and behind the speakers. Use curved walls which are double-insulated. Insulate the ceiling and floor. Sliding glass door (heavy and double-insulated) on the front with heavy curtains attached to the front. Put 5 dedicated outlets inside, along with an adjustable fan and a vent hole to outside. Create a small hole on either bottom side to run your speaker cables, and pack them full of some thick cushioning material. Have an isolated ground for your dedicated outlets with an audio-grade grounding rod (one for analog, one for digital). Look into audio grade wiring (8 gauge). Consider adding an ExactPower PowerCore and Conditioner. Put a HRS rack inside the closet. Then there will be nothing further to do.

I'm sorry. There is one more consideration for isolating everything from the floor. The floor inside the closet should be built on their own floor joists that are separate from the room and the closet wall. An elastic skin can be used between the joist and the flooring.

Now you have ground, air, electrical, and component isolation.

Consider a thermal alarm inside, in case of fan failure. There may even be a way to set the fan on a variable speed thermostat.