Room Acoustics, minimal treatment and measurements

Afternoon all.  Thought this might be helpful to some with wondering if room treatments can help with your 2-channel, and how to help visualize and measure what you may not fully grasp hearing wise.  I am just using a Mac Laptop and cheapo microphone, and REW, and 6 insulation panels.

This is my Step Fathers system, and pretty much empty LARGE  basement listening space.  There is a LOT of echo-reverb-ringing that (to my ears) over excites mid to upper frequencies, like being in a busy store/restaurant. With music, this can in ways help make a recording sound like it's in a larger studio/hall/space, but it also mashes a lot together and can over-color the music.  This results in lost focus and change in ACTUAL recorded acoustics: so an intimately microphoned musician will sound like an empty room, where an empty room sounds like an empty gymnasium.  This, also over-washes a bit of the mid-range and higher bass-losing it's tone and timbre.    Major thanks to @erik_squires who has been gracious to help with this process with dead-on advice.

FULL BASEMENT MEASUREMENTS:
34'long x 22'wide x 10'high

LISTENING AREA MEASUREMENTS:

15'long x 22'wide x10'high

Empty room, no treatments and RT60 plot.  Listening seat is *in the middle of the whole basement space, under an 18" boxed beam.*

"Treated" room, with RT60 plot.  Notice the overall mid-upper frequency taming from 700ms of "ring/decay", to 500ms.  Even with this, if you snap your fingers, you still hear a flutter echo.  This is from the whole other half of the basement room behind me, mostly.

Crude room response measurement:



Sketch and measurements of where things are in the listening room:


I hope this is helpful and gives you some things to try out that don't cause major disruptions to your system, until you really determine if and where your issues are and then you can buy and mount things.  My next step is to see where ON the walls I can place absorbing panels, and how many might be needed for a nominal improvement.  My thinking is the bigger issues are the ceiling, front wall, and then 'filling' the space behind the seat just to eat up ambient stray ringing.