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

I agree 100%. I've had a system in a number of different room sizes, shapes, ceiling heights, etc over the many years that I've been involved in this hobby. In some locations, I could hear the issues. Wasn't smart enough to do room treatment.

My son is a musician and has recorded in a studio and done his own recordings. He's way more knowledgable about the techie end of those things. He was absolutely convinced that I would benefit from room equalization, so I downloaded a trial version of Dirac Live and bought a recommended mic. He measured my room and we found that it actually measured pretty flat.  We tried the room equalization and didn't like what it did. It seemed to flatten the sound. 

At one point, we had the mic near the sitting position and we were getting a spike in the graph (I can't remember if it was a spike or a dip). It was weird. I had my laptop on the coffee table in front of me. I closed the laptop and the spike/dip went away. Pretty surprising because the mic was quite a bit higher than the laptop. 

I'm sure I could benefit from room treatment, but I'd need to get someone knowledgeable to help me figure it out. 

Best $500 dollars that I ever spent was DIYing a case of 703 Owen’s-Corning rigid fiberglass panels. 

I agree. Last year I bought GIK diffusers, absorbers, and corner bass traps. Made a huge difference in the performance of my system.

I would add this. “A person’s hearing ability can totally wreck or make their audio system “. My gut feeling tells me that many audiophiles having hearing deficiencies but don’t correct them. 

I built a new house during the pandemic and the new listening room was unlistenable. I pretty much abandoned listening to music and really struggled hearing TV. We’ve been using captions to understand the dialog. 

Then 6 months ago I upgraded my AVR and it came with Addyssey room equalization software. It was a hallelujah moment. Just like that it was magic. It was so good i upgraded the Dirac Live full bandwidth with Base Control with a good studio microphone and it is pure joy. If you have an unmanageable room, you might want to look into a quality room equalization solution. It worked for us.