The distance from speaker to wall is less critical than manufacturers claim. It does matter, but close vs far both have upsides.
What matters most is symmetry within the room. Your speakers and listening distance should be symmetrical, yet the distance from the speaker baffle to each surface (ceiling and floor included) should be different, so that SBIR (speaker boundary inteference response) does not overlap. SBIR is basically what happens to the energy leaving the baffle. The closer your speakers are to a boundary surface, the higher in frequency the reflections are, and the easier they become to absorb.
SBIR calculator
tripp.com.au
7" is enough space for a good amount of absorption, you could almost entirely absorb the front wall SBIR. A piece of 5.5" mineral wool with 1.5" air gap would have 80% absorption until around 225Hz, and 50% absorption until around 125Hz. If you don't want to build your own panels, companies like GIK sell similar products, albeit at a 2-3x markup.
The patented Monster Bass Trap with FlexRange Technology is our most effective panel measuring 7.5” thick, it absorbs maximum low end without over absorbing the high end.
www.gikacoustics.com
Room correction software can correct frequency response but not the physical domain, meaning the reflections still reach your ears and you just pull down the on-axis sound to compensate. Some reflected energy is a good thing, but you want to eliminate the problematic reflections, which in a typical room occur below 400Hz.
