Yes, sound needs reflections, but there's a reason acoustic panels exist. Kef did not build that speaker, then just throw it in a room with no treatments to measure it. You have many reflection points in a room. There is such a thing as over treating the room as well which will also change the sound, in a bad way. Almost any room you've heard speakers in, be it best buy magnolia or a av dealer, has had the room acoustically treated.
I'm pretty much just saying it's better to spend less on speakers and put the rest into acoustic panels. You can throw $500 speakers into a properly treated room and get better results then $2500 speakers in a untreated room.
I don't claim to be an expert but there's 2 things I know, cars and audio lol. I got f's in school, by the handful, but audio interests me and I retain most things I learn about it. If you can clap in that room and hear it reverberate (I'd bet on it), you won't get close to the potential of those speakers. Thats a basic test for testing acoustics of the room. Maybe low volumes you'll be ok, maybe you won't notice high volume fatigue. Fatigue is caused by our brain interpreting what the speakers should sound like. Filling in nulls and trying to reduce the peaks. Acoustic panels absorb the reflections that our brains have to compensate for. So you also help yourself and everyone else with the volume causing fatigue.
There's calculators for wall coverage percentages, also how to figure out reflection points. This is because like you said, sound needs reflection. Too much or too little is the problem. If you have 5k, go look at ats solutions website and research acoustic panels and reflection points.
I've had someone tell me my $500 LCR and $1000 8 12 sub setup sounds better to or as good as their family members setup which consist of high end audiophile brands that I dream about and frankly I'm jealous of because it cost more then my house. He may have acoustic drywall at most, the very best dirac EQ/DSP to back it up. Placement matters first and foremost, acoustic treatments matter at a close 2nd. I think after those two are met, you will hear the differences much better between 5k and 500 dollar speakers.
Let's just say, there's a better way to spend 5k in my mind.
- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -