Ok, finally I moved to a new place and installed the traps etc.
The sound quality is alot better once again. The walls are concrete so the room is more sensitive to standing waves and it shows when you move around the room but wihtout the traps the situation would be alot worse. The frequency response is quite good and neutral at the listening point. The room doesn't decay much in the higher frequencies and at first it felt very weird. As a result, the stereo image and depth are alot better and accurate. I still attenuate 130hz and 350hz a little with a software eq in logic and all system sounds go thru that master eq. Anyway, I am quite happy now.
