Well, it is possible to "force" a deeper bass out of speakers. I thought of: Linkwitz transform.
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Nothing I've tried myself. Should work but it should be at the expense of lower SPL for the same distortion level, or higher distortion at the same SPL. Compromises in other words. If this is the case, I am not completely sure, but intuitively I can guess that this is the case.
You can extend the low end frequency at the expense of maximum SPL in the rest of the spectrum. Essentially tilting the response. You will not get higher absolute SPL in the bottom, but you will get higher SPL at the bottom relative to the higher frequencies.