Sound Absorption Behind and Between the Speakers?


Recently my system moved to a new listening room and I was not enjoying the sound very much. There is a window between and behind the speakers. Last night, I put three sound absorbing panels right in front of the window and added a couple salt lamps which illuminate the panels. The sound instantly became way better! I have a soundstage now! I am not sure why though. Do the absorbing panels really have that much of an effect? Or does the fact that I added the panels with the salt lamps give my mind a surface to project the soundstage on which makes a bigger difference? Bit of both?
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I know this topic gets very complicated, very fast, but why does the space behind and between the speakers make a difference to anything but bass -- if the speakers have forward facing drivers?

First reflection points on side wall, ceiling, floor -- I get why they might mess up soundstage, balance, etc. But behind the speakers -- how does that affect these things?

Your answer will be directly relevant to my situation because I have brick behind and between my speakers. I think it's not *that* pure a reflector but it's not a diffusion panel, either.
It’s a good question! I wonder if flutter echo between the glass and the wall on the opposite side of the room plays a role because you are right: most of the sound (at least at higher frequencies goes forward, not behind the speakers. 
I ended up adding two absorbing panels behind my speakers and it allowed me to fully open the rear port on my sierra raal towers from ascend acoustic. Without the panels I had to use a partial plug that blocked the outer diameter of the port because the bass was overly muddy. It is now a fuller and tighter sound. And I find that diffusers are best at first reflection points on sidewalls and ceiling and on back wall and back sides of side walls. At least in my house of stereo and for my taste. Never made sense to me to have diffusers on front wall behind front facing midrange drivers and tweeters  since diffusers only diffuse higher frequencies.
@hilde45, the reason for treatment on the front wall is to control first reflections and then help on the axial direction.
Absorbtion and Diffraction (either / both) works above 500 Hz.
Bass Trap Placement is at corners and at ceiling / floor / wall intersections.
A lot is happening in the immediate space around a loudspeaker beginning with radiation pattern / edge diffraction / port energy / cabinet /
stand resonance.
Drywall has a relatively high absorption coefficient, foundation walls are well damped but highly reflective. 
Reflections aggregate / accumulate and decay in time domain (waterfall plot).
Look for a balance ...