Dave, I don't mean to be contrary, but no matter how enjoyable, a trip to the concert hall, or hearing sparkling voices singing in a large beautiful church is, you are dealing in the realm of impossibility (or close to it) in regard to creating this in your listening room.
In regard to DIY and room acoustics, the first thing is "define" what the room treatment has accomplished that makes your listening experience so much more pleasurable. Although our "bass traps" look as different as night and day, they both trap standing waves.
http://www.acousticsciences.com/products/tube-trap
Notice how those tubes resemble "rug cores". That is just one example of DYI in regard to room acoustics. The improvements delivered by correcting room acoustics are astounding; they are like night and day when compared with, and without.
No Dave, you haven't "hijacked" my original thread, which is basically about achieving "Class "A" sound as cheap as possible. More correctly you have re-directed it to room acoustics, which might yield more improvement in audio than some other things.
Those room treatments in the link above are stunning, and they work. There may be ways to duplicate them if funds are not in hand to purchase them.
Enjoy the music.

