Very large room HT

My room is just as big as yours and I power my room with all Revels. It's utterly fantastic. I suggest--strongly--you consider auditioning the Revel Performa 3 line. They will make you very happy in both music and movies. You'll get the dynamics and the ability to move the air needed in that space. You can also look to Emotiva amps to power everything you need. If you don't want to consider Emotiva, then think about Rotel's class A/B amps that they just released. For the preamp, think about an Integra, Marantz, or at the upper end of your budget you can spring for an Anthem 50v 3D edition. You should be able to do everything you need for 20k with those electronics and speakers and not look back.

Since you have limited choices for listening to new equipment, you may want to try something used from Audiogon, or a direct manufacturer with an in-home trial period. If it's Audiogon, you can always resell.

I'm a B&W fan, but they need a high-current amp to really sing. I'm not sure that best buy would have anything appropriate. There are always great options on Audiogon.

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TV..? Dude, with a room that size, you have to get a projector. I'm sure if you check the Videophile laws in your state, you'll find that it is illegal to have a room that size without a big screen and a projector.
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Used used used... for everything except the processor.

higher end speakers are cheep used and the people that buy them usually keep them well taken care of. save the money! and get better performance at the same time.

two of the larger type subs would work well. you can go new with those if you wish... the usual suspects would work great, svs, hsu , ryhmik.....etc.

can you control the light in the room? if so there is no substitute for a projector (i know you said you have a tv) you can get a real good used on e that is 1080p for CHEAP. make sure you research for the projectors and the screen to match your room.

Amps... that's a hard one, depending on your speakers.. how low the impedance goes, efficiency etc... need to know the speakers first... BUT....
parasound, b&k, anthem all make real good mulichannel amps.

i have a similar room 25' by 25'...dedicated ht, i use half for a billiard table.

my setup is...

110" Stewart filmscreen made for my projector
Sony vpl vw 60 (black pearl)
b&w 802n for the fronts
b&w htm1 center....don't skimp on the center speaker!
b&w 804S for the rears
anthem statement P5 amp
paradigm servo reference 15
marantz av8801 pre amp

send a pm if you have any questions as i do not look onto the forums that much.

Bill