As mentioned earlier, placement of your speakers has a lot to do with it. Try putting the speakers 1/4 of the way into the room for each wall (for example, if your room is 10 by 12, put them at 2.5 by 3 away from the wall). If this dramatically reduces boominess, then you will know what to do.
For a boomy room, what panels will reduce mid-bass
My listening room must have standing waves, because at my listening position there is too much mid-bass. It sounds bloated and the bass is just too pronounced. What acoustic devices are VERY good at reducing this boomy bass in the room? Panels on the wall would be nice, but I need something very effective.