If you have already ruled out any further tuning of speaker placement, or listening chair placement, before you can determine what types of room treatment will help you need to identify the frequency(s) at which the problem (boost) occurs. The lower the frequency the harder is is to kill without using a parametric equalizer. The size of absorbent devices, effective say at or below 60hz, can be problematic for a lot of folks, especially wives. :-)
FWIW.
FWIW.