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Congratulations on your new project!   I've given it some thought and I think the Plutos will lock you in to the amps you have indefinitely due to their lack of efficiency not to mention cause you to likely run a subwoofer during two channel playback.

The ERR's will work fine.  In fact my room is almost the same as yours except the ceiling is cathedral.   I have used the ERR's placed 24 inches away from the front wall which is my screen and point them at the screen (wall) rather than directly at the listening position.  This direct reflection increases the size of the image.   The low ceiling just above the screen (like yours) serves to reflect sound back onto the screen in an even wash.  The result is voices actually track the performer on the screen when they talk.  I spent 2 years trying to achieve that effect because with a screen that big it sounds completely stupid to have the voices coming from a small point either above, below, or centered behind the screen.

To keep the efficiency matching with the the Left and Right, I use two ERR's for the center channel.  Being pointed at the wall, a single center channel is 3dB quieter, so we use two.

Anything other than the banded cherry finished is considered custom.  However, I will extend the 30 day trial to the non-banded finish because of it's popularity.

3 vs. 4 ERR's I touched on earlier.  If I built you 3 vs. 4, and you didn't like them, the 3rd speaker would not be refundable.  We build ERR's in matched pairs.  Also if in the future you elected to go a different route, it's easy to sell a pair of ERR's but impossible to sell one.

Ok, the FRX...  

If you're going to consider these, the center channel issue must be dealt with first.  You could either put one in an infinite baffle or 16 cubic foot box behind the screen - the farther back the better.  Then a pair of ZOB for the left and right mains.  Of course the giant center channel effect described earlier with the ERR's would not be possible.

Sound wise the ERR's are a warmer speaker with more bottom end and lower bottom end.  Their midrange is more laid back than forward and they perform well in untreated rooms.  The FRX are more articulate and dynamic to the point of possibly sounding like crap with your quads, require tedious speaker placement and room treatments.  You might have to go with top grade low power tube gear to get them to sound right.

Rear channels,  the DM945's are a nice option because of their size and the fact that they have real bass.  Something I've grown to appreciate in rear channels as you feel the explosion come from the direction it was in the movie, even when it's behind you, which it often is.  That said, against a wall or in a bookshelf, depending on the acoustics of your room, the speakers could become boomy due to the rear port.  In either of your scenarios you would probably have to stuff the rear port with fiber fill to flatten out the response.

Amps,

I see no issues with your quads other than possibly with the FRX.
As far as tube amps in a rack, Our 2 watt amps generate the same heat as a 70 watt light bulb.  The 25 watt amps are the same as a 120 watt light bulb.  With proper spacing and a small fan it's seldom a problem unless your room is in desert climates with no air conditioning.

Hope this helps!

Steve

Steve, I have pretty much settled on a 6 ERR setup to go along with the Ultra and Toriis I have on order. I have a couple of questions on the suggested use of dual ERRs for the center channel:

1. I haven't settled on an amp for the center channel just yet, but am thinking of running the SE84ZS in bridged mono mode, driving the two ERRs in the center channel. I will have the two Toriis on the front and surround. Will the ZS be a good match in that setup?

2. Whether with the ZS or some other amp, how should I wire the two ERRs? In parallel?

Greg

Thanks mac5u. I think this will be fun. PM'ed you back.

Well, I can give you my thoughts as I read it, because 30 pages is a bit more than I'm up to in one sitting.


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My thought here is of course why would it take 100 years of psychoacoustic research when we're likely going to be discussing the physical properties of sound waves...

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Yup.

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Assuming you don't move your head.  IF you move your head left, the violinist will appear to also move left whereas in real life, the violinist would appear stationary (which is actually moved to the right relative to your head that moved to the left).

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No, I think it's better explained by what I just said.  The problem with stereo vs. real life, is that stereo only works if the listener is not moving.  In real live we move.  Anytime there is more than one sound source there MUST and WILL be differences in level, arrival time and frequency response.  In the real world, even with a single sound source there will be reflections.  Of course I'm picking on the wording of the paper more than anything here.


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Again, assuming that your head doesn't move placing us no more closer to real life.

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This is not the trouble, it is in fact the solution to making a 3D image from the less than perfect two speaker stereo system.  While easy to think a divider from the loudspeakers to your nose to prevent crosstalk would be the answer, this is what we get from a good pair of headphones.  Headphone users will tell you that without crosstalk the sound appears to come from inside your head directly between the speakers.  To stop this annoying effect in headphones, carefully designed crosstalk is introduced so that at the correct frequencies and amplitude left channel information is introduced into the right ear cup, and visa versa.


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Not sure it actually does unless we stick to the ridged model defined above of a live violinist standing exactly in front of you.  A model btw, that is useless in reality because sound is almost never directly square on in front of you.


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Yes, this is what happens in the imperfect stereo playback approach, that fails when the listener moves, but so far no argument that this paper we're reading will solve this problem.  Incidentally, Bell Laboratories gave a demonstration of three-channel stereophonic sound on April 27, 1933, with a live transmission of the Philadelphia Orchestra from Philadelphia to Constitution Hall in Washington which if you try the same thing at home AKA mono center channel, the image shifting effect when you move is LARGELY reduced.

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This is certainly true, and supports my average distance between speakers of around 6 feet regardless of room size.  And the observation that even closer together than that it is still fully possible to create a listening arc of close to 180 degrees.  

It's at this part in the argument that we have to start being specific about the equipment.  A simple triode amplifier with no feedback on a good source can make an equally good speaker disappear regardless of where you place it in the listening triangle.  However, a mid-fi amplifier on the same speakers will kill the effect - meaning you will hear sound come directly from each speaker cabinet.


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Easier maybe, but certainly not easy.  The crosstalk is actually increased not decreased because the speakers are closer together -  placing them also closer to the listener than before.  What is changing is the time delay.  The delay is shortened, and the ambient reflections from the room are reduced in amplitude compared to the direct sound from the speakers and relative to how loud those reflections were before the speakers were moved closer together.


My gut feeling about reading the rest of the paper is this:  If it's based on mathematics then it's likely assumed my comment about a speakers ability to disappear with a Triode Amplifier vs. a typical Solid State amplifier are not considered - making the entire paper void unless applied only to the world of mid-fi.   On the other hand curiosity might get the best of me and I'll read it anyway.

For now, I've had my fill.

Thanks,

Steve

Sorry Steve. Hope it didn't feel like a complete waste. But I sure do appreciate your insights. I loved this:

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Made me laugh out loud.

But this really helped to put it in perspective:

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I plan to do exactly that with my Ultra, two Toriis, 84ZS, and 6 ERRs.

Cheers!

Greg