I don’t know. I’m reading a lot of doom and gloom about your room (sorry for the rhymes), and no doubt there are a lot of reflective surfaces to contend with, but, it seems to me, the size of your room is a plus. Open baffle speakers by design are supposed to be more forgiving when it comes to sidewall reflections and boundary issues generally. I think once you have carpet down, or floor rugs, furniture installed, and art and whatnot on the walls, you’re going to have a much more subdued acoustic environment. I would suggest moving the speakers a little closer together, which will further reduce sidewall interaction and may help clarify some of that diffuse quality of the instrument placement in your image you’re describing. I would also suggest you pull them a bit further into the room, which will reduce boundary issues with the wall behind the speakers. Sitting nearfield will definitely help reduce side reflections, but can be peculiar in a living situation, and moving the speakers both in from the side walls and out from the wall behind may give you close to the same result. You won’t really know what you’ve got until your rugs and other furnishings are in, but I’m betting those, plus these small speaker placement changes, will make a big difference. In any case, it won’t cost you a small fortune in panels to find out. But I don’t think you should despair of your room being suitable for audio. Bigger rooms are easier to cope with than smaller rooms. I bet it won’t take much to make your room as good as most home setups. Good luck.