I don't know jackshit about many things. I couldn't figure out why my studio monitors became so bass heavy that the highs were muddy. I thought of ways to compensate when mixing, but I was pissed. These monitors though inexpensive had been great. I was pretty hopeless about any solution but buying new ones. 20 minutes I got a solution, and I have a good idea what happened. I moved them away from the wall and have my desk and them facing the middle of the room. The bass response when they were against the wall was muffled for the perfect balance.
The solution--which most of you guess: stuck rags in the back soundholes. Simple. Monitors sound great again.