[FrankGIK]

Okay, check it out...I think you can fix a lot of your issues just by reorienting yourself so that you're firing down the length of the room rather than across the short width. Take the white couch and move it to the long wall next to the red one, then move the mix position so that you're facing the window. There you go...now you've got over 6m behind you, and that puts your primary mode down way, way lower than the 3m dimension would give you.

So, having done that, I'd scoot the listening position out just a bit from the wall and get a couple of 4" panels on stands (or not on stands) behind it in front of the window. Maybe you could get 4" panels on stands for the right and left reflection points. The back of the room is open, so there you have it...

Once you make that move your mixing life will improve DRAMATICALLY.

Frank