The first step with ANY sound issue is finding the best placement of the speaker. While moving speakers away from the corners of the room will reduce boom, a more precise way to find the best placement is to use one of the methodologies that involve systematic placement experiments. Look up the "Sumiko Method" of speaker placement. This involves moving the speakers in very tiny increments to find the location where bass is in proper balance. You will be surprised by how even a movement of less than an inch can make a dramatic change, and because room modes can be all over the place, it is not necessarily the case that the further from the corner or walls one goes, the less the bass boom. Likewise, experiment with placement of your listening chair.
As others have mentioned, experimenting with a change in loading of the speaker by stuffing the port is also a worthwhile, and cheap, tweak. After that, there are more costly approaches such as DSP room correction, subwoofers, room treatment with bass traps, and so on.
As others have mentioned, experimenting with a change in loading of the speaker by stuffing the port is also a worthwhile, and cheap, tweak. After that, there are more costly approaches such as DSP room correction, subwoofers, room treatment with bass traps, and so on.