rooms and sound levels

Any of you folks know whether a room has a specific sound level that, if gone over will cause a decrease in the clarity of sound? I find that my system seems to blare over a specified level depending on the cd played. Anyone write an article about this subject? I'm building bass traps at the moment, but the blare seems to be noticable in the mid and trebble, which is why I pose the question. It sounds clear below a certain level with no hint of distortion. Would a diffuser be of value? Has anyone had experience/benefit from the monster surge protector/ conditioner, which retails at about $300. The small 8 or 10 plug wonders?