Hi Milpai,
the room is a cellar room, so dimensions are a bit tricky. It's footprint is fairly big (9meter x 4,85meter), but the usable space (where I can walk around) is 5.5 meters x 4,48 meter.
The speakers are now about 110cm from the back wall, distance between them is almost 3 meters. They do like space around them!
Biwiring them is also on the plan, thanks for the reminder :)