If I had issues with any frequency, I would look at the source first. I have a difficult time with some of my older media, THEN the room. I say that tongue in cheek. Both have to be right to make a call for tone control. If the room and source are good, I have to do very little with a full range speaker. Set the controls to flat and away I go.
I use GR servos and DSP Bass management I also use Helmholtz tuning with 2 100cf tuning resonators on the front wall and 4 adj traps on the side walls.
I EQ the room just like a graphic and parametric. I can actually notch single or multiple spots or tune around to lower SPL with a lower region. It can’t correct for suck-out or combing but if the room is tuned 1/2 way right you won’t have that problem.
If all else fails, tone control or a graphic EQ will work just fine.
Loudness trim is what made Mcintosh controls so nice. My personal favorite if I’m using a NON "Line stage pre". Currently I’m using a SLP-05 Cary.. There is ZERO tone control there. Most of the media is working out well enough. I still have LPads via speaker XO for treble and mids. I have a little wiggle room. 280hz and below has always been the greatest challenge in any of my rooms. Once I clean that up, the mids and highs are easy..
Helmholtz the only way to fly..