Most everyone who has tried room acoustic treatments has experienced it. They are essential, if you have a room where they can be hung properly.
Room Treatment Surprise
I have really lousy dimensions for my listening room ... 10x10x8. I use B&W N804s and recently added a subwoofer. Then, I got the bright idea to treat the room with corner bass traps and a few other items from GIK Acoustics. This has proved to be a huge upgrade, probably better than at new component. I find that I no longer need to use the subwoofer unless the recording is bad sonically, in which case a little overall boost is necessary. Has anyone else experienced this type of thing?