opivl.. What you hear is what you hear, and what matters for you. I don't do Rock, but I do listen to some Jazz (loud dixieland) and some bluegrass. With my crossover at 70Hz, 24 dB, I observe that what sounds like a lot of Bass, usually doesn't make it down to the SW range. Bass drum in a CD of Sousa marches , and Bass Drum in some Gilbert and Sullivan recordings and the cannons in the 1812 Overture also exercise my subwoofers, but organ music (and not all of it) is the only thing that gets the SW amplifier heatsinks warm. Cannons, by the way, are even "slower" than big organ pipes.
You might be interested to check out the frequency response of pro-sound speakers...the kind used by rock bands. They don't go down that far... they are built to play LOUD! They make lousy drivers for a home-brew subwoofer.