Anyone running 9 or 10 speakers in their HT setup?

" I've stayed awake nights trying to figure out a way to replicate the incredible sound that I heard in that theater" (Mitch4t)

There's really a lot more to great sound coming from these "IMAX" systems, than simply MORE SPEAKERS. You are usually dealing with VERY high efficiency, pro, active speaker systems (I think IMAX theater use an "active" speaker array" of some sort - I used to know the names) in these large, acoustically advantageous movie venues, as well.
The fact that there are often "more speakers" in the theater is usually required for better, and more approximate coverage for hundreds of seats. Yes, the multiple speakers makes for even more dynamic ease through out the space - but the real advantage with the speaker technology there is the ulta-high efficieny and power for those systems! These active horn sysms dynamically stomp the living bajesus out of what you find in most passive home systems, indeed! You're looking at some 115-118+ db of efficiency, couple with "active" speaker desings (drivers coupled dirrectly to the amplifiers, with active cross-overs), added with bass management to boot! We are talking serious dynamic realism and capabilities, which make standard home stuff pale in comaparison in reality. That, and they area also using master audio for the sound.
And, yes, the theaters are dealing with some rather sizeable acoustical advantages, as well.
I think you can add up all the variables that comprise the sound you hear in your playback system, acoustical issues, setup options, speaker technologies, bass management and power distribution and efficiency (receivers are more limited than separates amps in terms of power delivery, IME), among other things, and you start running into limitations with most typical home setups - not to mention lack of understanding from most people who setup their own systems, for less than balanced speaker and seating placements, settings, phase issues, etc.(not specificially you or anyone, but most, for sure).
Basically, I'm saying you need to consider what's behind producing "great sound", in-whole, and not just the shear number of speakers in a system - full range, or not.
Actually, that brings up another issue. Simply running large full range speakers in your typical domestic acoustic home spaces, is not simply going to give you advantages. Infact, often if offers dis-advantages along with it. So consider. Full range from passive speakers is often more in-efficient than crossing over to active subs, as is usually the case! Infact, in those EXTREMELY large movie venues, even those otherwise full range 15-18" horn speakers cross over to dedicated subwoofers, for good reason! EFFICIENCY!
I would rather like to see you make sure that you have all your current speakers and your system properly setup, to assure relatively flat response from your listening area, proper phase between subs, speakers, and seats, proper balance of sound, speaker aim, soundstage width/perspective and acoustics. With a proper foundation securely anchored, I think you can then consider more speakers (as long as you can set them up balanced for good sound and coverage, is the key - Note: you can place speakers so they don't properly cover an even tonality and response from all seating positions, real easy)
That all said, you should be able to try experiementing with additional "matrixed" front and back effects speakers to your hearts desire, for maximum envelopement, yes!
Balance is the key however, so remember. You mix that with proper setup, bass management, speaker settings and locations, flat response, perfect phase, efficienc system, acoustics, etc, and you have one heck of a system potential!
So I say "go for it", if you've laid the proper foundation, bassically...you can build your sonic pool of sound from there.

If you want to get additional speakers with your current setup connect Y splitter interconnects to the signal out on your processor to connect 2 amps/speakers to 1 channel. I did this to have 2 center channel speakers under an 8 Ft screen to fill up the center and keep the volume down. I don't have any comment on how this would work on the surrounds

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Naked.......Great post, I appreciate it. Now I can sleep peacefully now that I know what I'm up against.

Somec.....I had already been contemplating just what you mentioned in order to get addional surrounds for more area coverage. My center channel is 25.5 ft from my listening chair, the fronts and rears are 30 feet away. I'm sure with an addional four speakers that I'd get much better coverage. Currently, I have to crank it up pretty good for sufficient area coverage.
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08-11-08: Mitch4t
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The IMAX screen I saw was six stories high. You could tell when the IMAX shots were on the screen.....the on-screen image filled the entire screen. The 35 mm portions of the movie of course were letterbox style, still outstanding though.

Then you saw it in a real IMAX theater. And while the image quality in letterbox was good, I noticed quite a drop in resolution compared to fullscreen IMAX shots. And I could be wrong, but I think the letterbox portions were shot in 70mm.

Concerning your question about plugging the DMP-50's 5.1 outputs into the Sunfire, AFAIK the analog inputs are a bypassed analog pass-thru, so you also bypass any of the Sunfire's internal digital processing. So if you want to send that 5.1 signal to 7 or more speakers, you'll need to do it with Y-adapters.

And once again, I need to follow a poster's link to his System pics and equipment list before I start pontificating on how to fix it. Your viewing/listening area is huge and unbounded. In that case, you could use extra speakers or wall in your viewing/listening to get boundary reinforcement.

Still, I don't think we can equal the soundtrack performance of "Dark Knight" at home until we have an uncompressed audio surround source. As Steuspeed said, except for rocket launches, IMAX surround is essentially 5.1. But they have an uncompressed audio source and use both prodigious power and highly efficient horn-loaded speakers to achieve an exceptional dynamic range. And they have a subwoofer enclosure you can walk around in.

Mitch: That is a very large room, can you hangar a plane in there? Don't know if this thread is dead yet or if this is helpful, but, any though on using both the XLR and RCA outs simultaneously on a processor. I e-mailed Meridian last year and they said its OK but the volume levels will be different, which requires an attenuator.