If there is cancellation ( we are getting rid of wave off of rear of cone/diaphragm ). If we are combing signals in a 'node' , there is still that . Output will be less loud/lower , you might be able to hear a little more 'clarity' around transients ( sudden changes ). Next , up LowPass crossover by 20 hertz , if graph does not register increase in frequencies , beats me !
Grinder & Smitty are here , they will think of something .