For speaker placement-
First big choice is do they go L/R across the long wall, or the short wall? Room layout might dictate one or the other and if so no worries. But if not then the only way to know is to try.
Next big choice is speakers and listening chair, how far or close to the wall? Several feet away from side and back walls is great for imaging but you will notice distinctly less bass. Sitting back near a wall you will get a lot more bass, but not as good imaging. No right answer, whatever you like is best.
But think about, will you be using just the two speakers? Or adding four subs in a proper distributed bass array? If DBA you can forget about bass for now and focus on imaging.
Doing this part I find it easier to remove any speaker spikes and not fuss much over placement, toe-in, etc. The goal is just to find where you get the smoothest most even bass response.
Now hopefully you got these OC703 panels
https://www.amazon.com/dp/B00BJMX5P0/ref=sspa_dk_detail_0?psc=1&pd_rd_i=B00BJMX5P0&pd_rd_w=i...OC703 is real easy to work with except it does make this fine irritating fiberglass dust. Cut it with a razor blade or sheet rock knife, outdoors or in a shop, wearing latex gloves and a mask. Its not that bad but you will be a lot happier if you do it this way.
Pick up a box of stick pins, not thumb tacks, little pins about an inch long. Cut two panels about 12x12. Place them on the side walls to catch the first side reflection off each speaker. Alternatively you could lean one panel against the wall, with another above it held with pins. This is kind of overkill but you don't cut anything. Again there's no right or wrong. The only way to go wrong is just start doing stuff other people recommend without trying to find out if it actually works! lol!
This is all an iterative process. Now go back and tweak the speakers. Using a tape measure set them up to be exactly equidistant from your listening position. Then using a laser level, framing square, or creative measuring point them precisely the same amount of toe-in. Listen for imaging. Experiment with toe-in. This fine tunes both frequency response and imaging. More toe-in, more precise imaging. More toe-out, wider more spacious but also more diffuse presentation. No right answer. Experiment. Only way to know.
Not easy. Lotta work. Do all this and if you are not stunned then I will be. Because it totally works.
And we are just getting started.
