Did you try toeing in the speakers? That would help ameliorate the open space behind the left speaker and the open space to the right speaker. I would try to aim them so that more or less the rear of the speaker fires into each corner as a starting point, and then fine tune from there. Moving them out anpther foot or so would also help. Pointing the speakes straight ahead will give a larger and more diffuse soundstage, while toein can give you a smaller souunstage but more focus on the images. How high do you sit in your listening position? Most people's ears are around 39 inches or so off the ground. Also, I realize space is at a premium in Parisian apartments, sometimes compromises have to be made.