Lets see your listening room dimensions.

I will admit I have a compromised music room. 12x20x8. My sister has a music room to die for. Asymmetrical as all get out. Angled ceilings with many corners. Walls are rectangular and is broken up by enclosed rooms coming out into the main room. I'm guessing room dimensions. 20x30 with height varying 10 to 15. The most amazing thing is that she has a late 70s stereo with NIKKO Components and OHM I speakers. Are you reading this John S.? It sounds unreal dumbfounding awesome. It made me rethink whats really important in the audio chain. To anyone who is shopping for a new house please take this into serious consideration. Your probably going to have wood floors that are not best for TTs and bass. I have made my own speaker isolation bases which are cheap and not a subtle improvement. Message me for details. Let me see if I can put it on my page here. Good luck. 
20" deep X 25' wide with cathedral ceiling.  A rug in front of the speakers is the only treatment needed.
We bought this home because my wife loved the kitchen and I loved what would become a great space for my stereo.

31 feet long, 18 feet wide and 12 feet high.

The room has slate floor with wool rugs covering about 75%. For several years no treatment other than ASC tube traps in the corners behind the speaker.

Since then I’ve gone full treatment and although the dimensions are on my side, professional acoustical treatments were a huge benefit.
2 rigs. The Quad ESL near field is one corner of 40’x26’x7’6" with beamed ceiling basement. The other system is the corner at the other end but is actually almost half the space at the other end.
I happened along this thread and am looking for advice.  My system is currently in a very large room 25' x 35' with 8.5' tall ceilings and it sounds awful.  Why, because my house is a mid-century modern built in 1959, and has solid brick interior walls.  Additionally, the right side corner and wall is mostly glass.  The back of the room is open but also has a glass divider.  Lastly, someone installed a large skylight that is over the left speaker.  Since this is the main room we live in and you see when you enter the home, treatments are not an option.  So, I have decided to look at other spaces in my home.  The first is my office that is 10 1/4' x 20 3/4' long, the next room is 12' x 13.5', both with 8.5' ceilings.  The office would be ideal but I don't know if the dimensions will work.  I can put as many sound treatments up to compensate but am concerned the 10' width may be limiting.  Very curious to the groups thoughts.  Thank you in advance.