"Research proved that in a live musical environment, approximately 30% of what we hear is direct sound while 70% is reflected from walls, ceilings and floors and only reaches our ears a few milliseconds after the direct sound. The human brain uses direct sound for identification and to calculate location, but uses reflected sound to determine musicality and spaciousness, as well as direction."
Right — and this is why a deadened room sounds "weird."
I appreciate the pushback on the way I phrased the OP. I think it is possible to have good rooms if mid or nearfield listening is possible. That said, the space I was setting up in was going to be near to midfield and it needed help.
At first, I way over treated it. I got a lot of panels for free from someone local -- bass traps, absorbers of different kinds, a couple diffusers. Put too much in and took a lot out — but not the bass traps nor the absorbers on my 6.5ft ceiling. Things were not right so I got a bunch of diffusers and they did the trick.