New home - should I build theater under garage?

I believe I saw a thread here of someone who actually did just that; had the spanned concrete garage floor and all. If I remember correctly, it was fairly easy to soundproof the room. I'll see if I can dig it up.

Edit: Found it: http://www.avsforum.com/t/1365438/bradley-concrete-cave-theater-construction-thread

Here is a spancrete in progress http://www.avsforum.com/t/1445270/27l-x-22w-x-10h-diy-concrete-bunker-w-eight-18-ib-subs

If I did my theater again I would put it under a 3 car garage with an equipment room, entrance, and bathroom under the house (at the back of the theater space under the main part of the house - leaving the full 27' or 32' length of the garage for the theater. As far as height goes, can you have them dig out the theater an extra foot or two to give you a taller ceiling in just that room? The main reason I would do a theater under the garage is because of the location. I assume the only wires & HVAC lines coming into the room would be for the room. So it would avoid having to deal with house infrastructure running overhead. They just had to open my ceiling up to fix something running overhead but not related to the theater itself. Under garage is naturally not going to have windows so a good use of space for a theater.

It would make sound proofing easier at least on the walls. Spacing your studs a few inches off the wall counts as double stud wall (according to Ted) so you can just frame the room without having to deal with clips on the wall (options vary for ceiling). Double stud is simpler, cheaper, and you can inspect after work instead of taking a few days off to stay on top of the workers (to make sure they do the work meeting specifications they've never heard of).

Wire, ducts, and tubes are pretty cheap. I would view the locations isolation as a good thing. That said, I haven't done it so can't recommend one way or the other. There may be a bunch of other issues I'm not aware.

Actually, my first choice was to put the HT on the main level. A big ranch. But other priorities for me made that unfeasible. 2nd choice would have been under the garage had I known about spancrete. 3rd choice would be what I did which isn't bad, just not a nice as I had hoped (so far). But all of the above are better than taking what you normally get with a basement and trying to retrofit a theater in there.

I'd vote for under the garage. Try for 9 or 10 foot clear from slab to spancrete. You'll eat up headroom with the ceiling treatment and risers.

Isolated AC and heat systems is a good thing in my opinion. Theater loads differ a lot from typical residential requirements. And you won't have to deal with theater sound migrating through ducts to the rest of the house.