Omar, you might find it interesting to study the "audible threshold" at very low frequencies used in the Ulimate AV sub tests . They don't describe how it was constructed, but it's apparently from equal audibility curve research conducted following Fletcher and Munson. Note that this is just for barely being audible. As a practical matter we're not likely to be hearing 20Hz(or for that matter, 20KHz)at normal levels used in home listening.

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Enjoy the music, not the equipment.