Your illustration, Dave, is the reason I am changing from my Bose for my upcoming dinner. Aside from constricted to six feet in a corner with my Bose telescoped over my head, all I could hear was loud bass, even though the guests, reportedly, did not experience the imbalance.
My point is that whether the bass could be adjusted internally is beside the point, as everything was balanced on KB before I left the house, and I don't want to fool with EQ at the job.

For this particular gig in a large hall, I need to hear everything, and dial my bass intensity and volume with a turn of a dial on my remote. This is in addition to stereo that is not confined to a sweet spot.

Thanks for your sage advice(NO tongue in cheek).