The only caveat is that bass does not respond to room treatment.
Kind of, sort of....
All my suggestions so far have been subtractive. That is, to remove sounds in the room. If you only subtract mid-treble then your balance shifts to the bass.
From experience and theory I can state that this absolutely brings out more bass and make speakers sound more powerful (I'd say larger but that sets some readers off into an irrational tizzy).
Will it fully fix the OP's issue? I'm not sure, but I do now his judgement about the bass problems will change after the room is treated.
Also, we want the room to interact a little. Diffuse sounds with a steady decay are really important to avoid a headphone-like experience and give us the illusions of the listening venue.