Hi Salva,
You describe my setup. I have the 1801s about 15-20cm from the sides of our entertainment center, which is 3 meters wide. We removed the fireplace stove that we had on the left corner to free up more room and we hardly ever used it. Instead of a window, we have a slider along the right wall.
Inspite of the large furniture, I have very good results with clear mids and extended bass. I admit that it took awhile to get used to the difference before we had the furniture. I think the depth of the soundstage is not as great. Though, it's still very good. Even though the 1801s exten down low, I like them better with my new subwoofer, SCC300 driver with Hypex HS200 amp in a sealed 4.0cf enclosure (I probably could have been fine with a smaller 3.0 cubic foot enclosure).
Enjoy,
Al