Well, your room is certainly big enough. Do you have acoustic treatment in the corners (bass traps)? And at the first and second reflection points?
Also, you do need to pull the speakers out in the room and away from the side walls if you have not (1/2 meter is not at all ideal), and be sure you have something breaking up the waves at first and second reflection points. If acoustic damping is not possible right now (because it looks bad), a tall plant (ficus tree, palm plant, or something with leaves that break up the reflections) will work well.
Room is EVERYTHING, something people forget. I have heard the same system in 3 rooms and in one room, it was....decent. Second room, good; third room was great. Exact same equipment ( know because I had owned it before I gave it to two friends). It was the room and how the equipment was set up. And acoustic treatment is important: Soft rugs or fabric woven art are great near the speakers. Or heavy cotton curtains (HP had one wall down the length of his listening room covered with a curtain on a rod. The curtain was thick and had folds in it). Other than that, he just had a piece of Sonex at the first reflection point near one speaker.
The room comes first.
