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

@onhwy61 your post is certainly true and reasonable. My experience mirrors what you stated. I have had massively to minimally treated rooms throughout the decades. I managed to get all the systems to sound very engaging and enjoyable. Natural wool rug in front of the speakers, more nearfield listening combined with speakers that work well with aggressive toe-in minimizing the room’s impact. Getting acoustic treatments right in a given room can be difficult. One of my highly treated rooms would always sound flat and a tad dull. I learned to use more diffusion and thicker broad spectrum absorption panels to avoid that result.

Furniture combined with book cases and such can certainly help acoustics if well thought out. Some of my listening spaces were in a shared living room making the use of acoustic treatments near impossible! 🙁.

Finally, I have a good audio friend that paid one of the acoustic companies mentioned in this thread many thousands to treat his room. He ended up having them remove most of it in the end. He felt the system lost life and vibrancy. I suppose some of this can be subjective in terms of sonic result. It seems everything in audio including acoustic panel types, placement and number, is also subjective.  Nevertheless, if at all possible acoustic room treatments should be employed, but realize it takes time and effort to do it your liking and preference.  
 

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!