"The room can totally wreck, or make, a system"

One last point. Many of these acoustic companies will offer to study your room and come up with 2 or 3 price options. I notice these plans all but wallpaper walls and ceiling with a great number of panels. I question this approach. Start slow and test with a few treatments and go in steps! 

"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.

@hilde45 

I understand that in the real world people are used to listening to their rather live rooms and it might sound strange in a treated room. But once your brain tunes into the sound emanating from the speakers you start hearing the room the music was created in, or at least the ambient space that was created in the mix. 

Sure, live music occurs in an acoustic space and that's an important part of the original sound. But a good recording captures that sound and that's what I want to hear. An untreated, live room distorts the sound in the recording  by adding sound that wasn't part of the original performance. No different than noise. 

A room needs both diffusion and absorption for different reasons. But the net effect of good treatment is reducing the sound of the room and allowing you to hear the recording without added noise, which is what reflections are. Noise that wasn't contained in the original recording. 

A good recording studio isn't anechoic but rather a place where music sound fabulous. Spend some time in one and see. 

 @decooney 

I hate listening on headphones. My point is that people who do like them don't complain about the absence of room sound. They like hearing the actual sound of the recording, not the sound of the room they're in. 

@grannyring  Looking forward to you hearing my room soon.

I have not posted a sweep of the totally untreated room, just the partially treated room (first reflections at sides and on the ceiling slopes)[orange line]. Regardless, having a room almost perfect wrt the Fibonacci preferred ratio (10x17x23) it still needed some serious bass trapping. Just a taste of what treatments can do to improve the room response.

https://www.audiogon.com/systems/10635#&gid=1&pid=9 

Today I have all 4 corners heavily trapped. The rear corner traps hide behind the Real Traps Near Diffusors (half diffusor/half trap). Those hidden traps are solid triangles of OC703 (your friend!) stacked behind the Real Traps units.

Good advice abounds here. Too much absorption gives you a dead and boring room. Some of us who built HT's found out they suck for 2 channel!

Equalization and room correction software can only change what a speaker puts into the room, they can't do anything for what the room puts out in reflections and  reverberation.

Acoustical treatments are easy to do, and easy to overdo. I agree that an untreated room can never be right. Home theaters are different beasts than 2-Channel listening rooms, but to a point they can effectively share treatments. Case in point is Acoustimac's Home Theater Room Package I for $848 you get 6 2X4 2" panels covered in your choice of fabric,or upcharge for artwork plus 4 48X24 4" bass traps, likewise covered. Add to that a couple diffusers and the improvement in most listening rooms up to 200 or so sq ft is dramatic.

Because of the room layout, I couldn't use an off the shelf package In our living room, so I had them make up 16 - 2X2 2" panels in ceiling white - they are practically invisible, but made a very bright room usable, if not great (lots of glass, no drapes)

In our theater, I went with a darker grey (light control - it's a theater)  ceiling panels and using a combination of white 12X48 and black 12X36 2" panels I made a 5ft wide 'keyboard' wall hanging that my gets lots of positive comments, and is very effective. I used 2X4 construction offcuts to make a 16X48 diffuser  using the BBC staggering for the lengths (Warning- it weighs a ton!) for the back wall.  

All in, I spent under $2K plus about $500 in hired labor to install the ceiling panels. I am very pleased with the acoustical result and the SAF is very high. Money very well spent.