Putting the speakers closer to walls and corners will give you more bass, and quite possibly too much bass. In such situations, you could try changing your listening location to one that minimizes the effect of this boost. Alternatively, a simple tone control might help alleviate the problem. Alternatively, if you are using a subwoofer, the setting a high-pass filter to the main speaker at around 80Hz will eradicate the problem. If all else fails, sometimes stuffing the rear vent of the speaker will help reduce the amount of bass. An old sock or foam ball can work quite well!