Ceiling is the one thing you can’t do in a living room.
Beginner improvements for room acoustics; very helpful Darko video on reverb and RT60
I often find myself trying to help friends new to audio take their first steps toward improving their sound. Taming room reflection is, of course, the first step.
Many respond by saying some combination of "Why would I need that?" and "Isn't a rug and furniture enough?"
Darko's video explain the answer to both of these questions, and does so by explaining in layman's language what the sweet spot for reverb typically is, and why furniture and rugs are not often sufficient.
He describes a reasonable, middle way between going all out on room treatments and doing nothing. At the very least, he says at the end, do the ceilings.
Again, old news to many here, but possibly of use for some here and for anyone advising others.