To better understand your answer did some further reading and came across this:
A similar situation exists with home theater (e.g. “surround“) setups where the customer thinks that the front speakers are ”full range“. Even so, the best approach is to seal the ports, operate the 5 channels as ”small", crossover at 80 (or even a bit higher, but never lower) and correct the timing issues inherent in all modern subwoofers by setting (in the receiver or processor’s setup menu) all the distances the same, and to a small number such as 7 feet; then set the subwoofer to 12 feet more (i.e. 19 feet) and then use the variable phase control on the subwoofer to fine tune the relationship at the 80 Hertz crossover point.