@millercarbon +1,
Agree with the above recommendations. Distance from side and rear walls makes a huge distance in how the speaker will depict sounds, from bass through the entire frequency spectrum. I am a naturalist when it comes to to my room and music playback.
I invested heavily in my latest room build, you know, $45 Quietrock double sheet drywall panels, Roxul safe and Sound insulation, spray foam under all joists and eaves, Quietrock puddy on all outlets, resilient channel, and a scientifically measured room by the best spectrum room analyzer I know, “me”, using Rives Audio (now defunct) professional room measuring kit, Radio Shack sound pressure meters, Velodyne Sub EQ Measuring tool, and my ears.
With all of that…I spot treated room anomalies, bass, mid, or high frequency with the usual absorption or sidewall diffusion stuff from various vendors, Gik, Vicoustic. That being said, nearly the entire back wall behind the speakers are drystack stone. Well, it looks beautiful, but, this plays into my naturalist desire to hear music as if I am in an open or closed venue, think clubs, bars, or concerts, Those locations have no form of absorption and the sound is literally around you. This is how my room sounds, sometimes it sounds like I have surround sound because the music is so enveloping. I get stereo imaging “plus” I get the sound effect of the instruments, musicians, and recording or music venue ambience that adds to the stereo sound. It’s enchanting to say the least. When you experience how much better music sounds when it envelopes you, you will seriously consider why you restricted yourself to just only a plain stereo image, which is okay, but now that I know what I know about “natural diffusion”, my personal recommendations are that you should experiment with what you have as stated above, and see how you like it. Yes, a stereo image may be disrupted by the spatial queues, but that’s only after the initial direct radiating sound arrives to your listening position if you aim your speakers towards you. The delay I speak of (really low milliseconds here) adds to the ambiance of the music and it is really uncanny if your system has the resolution and ability to convey this back to you. Remember, I measure my room with spectrum analysis and my ears…my ears and all of my family and friends tell me that the rock wall behind the speakers sounds way way better than absorbers, spot diffusion behind the speakers. That’s my experience. Third room build, and each room is better than the last, but the stonewall will always be part of the equation.