Room Treaments - Where To Begin...

Now nothing except an optimal listening position an Vandersteen 5a carbons with the 11 band equalizer tuned to the room

An EQ??? Turn in your audiophile card immediately!! (Being sarcastic)

But but ….. it’s all analog and built into the speaker

They said it would be ok 😅

But I shouldn’t have said no other room treatments. I’m lucky that we have large openings to adjacent rooms at both first reflection points. And my wife pushed for American Clay on the walls. It’s literally clay and it’s the best cure for slap echo I have ever heard. We did the ceiling too.

My wife and I both heard an improvement and curiously mostly in the lower end, where it seemed like my speakers finally had some depth in some bass.

Yes!  I have written about this often.  Clean up the mid/treble and the bass rises from the depths. It's amazing how this can transform the sound of smaller speakers. It can make them sound huge.

@erik_squires yes, well I am certainly on board and can attest to it working better, I thought it might be from breaking up the bass energies. But on this I am still discovering what to do, well, at least I'm reading and muddling through it.

@fleschler about activated carbon filters, yeah I've used the Acoustic Fields QRD17 plans for four diffusers, and I'm deliberating building two or possibly three of their low frequency absorbers (I might even just break out the cash and buy them instead).
How much did you use? What sized room, and impressions?
I'd really like to know, sorry if I'm getting personal.

The best thing you can do, is to very precisely place your speakers by listening and using REW.

Take a look at the Before and after, with absolutely no room treatment. This living-music room is the most difficult room to make music sound good, vaulted ceilings, L shaped lots of little right angle little walls, a fireplace, and a lot of windows and skylights. On top the house is made with wood sticks, plaster walls, the wood floors are suspended, in other words a resonance box.