I tried a totally unscientific and subjective experiment yesterday by removing the side wall absorption at first reflection points, and removing the sidewall absorption/diffusion just behind me whilst leaving front/rear of room as is. (I didn't remove them personally, got my rather bemused mum to remove them for the afternoon)
Just so we're absolutely clear I have absolutely zero/zilch/nada/not a fucking jot of acoustic training so this purely based on what I heard, the room was set up a few years ago by a mate who works in the industry using rew/umik mic and his 30+ years of work in studios)
Front of room
4 tri traps with membrane range limiter, 2 4" absorption panels with tuned membrane and 1 4" absorption/diffusion
3 2" panels on ceiling
Rear of room
Rear of room with 8" bass traps with tuned membrane and 4" absorption/diffusion
I removed the 4 side wall panels shown below (old pic, ignore my previous krk's, these are all old pics)
I sat and browsed my usual listening of electronic/electronica such as Jon Hopkins, Craven Faults, Underworld, Moby, Carl Craig, Rival Consoles, Chemical Brothers, Daft Punk, Dave Clark, Loscil etc...etc.
The sound in listening position in front of monitors was undefined, less direct snap, less impact and the side wall reflections were rather annoying for my preferred musical choice.
So today the panels are back up and I'm a very happy bunny today.
This concludes my totally unscientific subjective appreciation of how my room sounds with/without side wall treatment