Increasing bass on floor standing speakers

Speakers on the long wall, I'd guess not much space behind the listening position then? 

Sounds like a perfect case for bass (wave) cancellation. 
If not quite that, figure out about any 'other' unintended bass traps in your listening area. 

I had this issue and only found out once I moved to another location. It can be subtle but annoyingly effective.
I know now. 
Bass problem, in the new location (speakers on short wall), gone like magic. 
Michélle 🇿🇦