Room Treatment? How important is it to treat the wall behind/between the speakers?

Thanks @kevinzoe I'm looking forward to getting some help with the REW stuff but in the meantime thankyou very much for all the suggestions and support.

2 other take away’s

1. There is significantly more agreement on this thread/subject of acoustics vs the many, many power cable threads (I am NOT a cable denier which should be evident from my virtual system, cables matter)

2. Anyone thinking about improving sound quality in an untreated room by swapping cables (or other tweaks) should pause and look hard at acoustics first  

@macg19  You're welcome. Just so you know I prefer OmniMic to REW but folks can send me REW data in a text file format to analyze.

Macg19, as you decide what treatments to place on your sidewalls (and front wall 1st order reflections), Energy Time Curve data for the first 10ms will help guide you towards symmetry both cross-channel (Left vs Right) and cross-octave (across several octaves but within the same channel) for tonal balance and imaging aspects.  

Here is a post I wrote somewhere else about "Before" vs "After" sidewall treatments that goes into a lot of depth and analysis - maybe too much for most - but shows the level of detail that can be used to guide the process. Beside the original post, I added two more comments (further down page 1 and on page 2) as there was too much to include in the original post.
https://www.canuckaudiomart.com/forum/viewtopic.php?f=4&t=69938

I'd put a panel on the two side walls in the upper corners, where you have two untreated parallel panes that are bigger than 2x2 feet. A lot of reflected ping pong is going on there from the way it looks (especially in the 1k -2k range based on room size). Since the speakers are near those corners, any omni energy from the boxes is going to hit those upper corners first.

Even a 1.5 x 1.5 panel on each side would help. If the room look is an issue make them the color of the walls so they blend in.

Anything to keep them from being flat would be better than nothing. It's not so much about 'reflection' in this case as room resonance between those two open areas.

Every speaker is different. Needs a different setup, needs different room treatments, to get the best out of it. Refer to manufacturers recommendations and go from there. Easy.