> If you want flat response but your music has lows that go down to around 20hz, the relative power required to make the 20hz audible to an equivalent volume is

> If you want flat response but your music has lows that go down to around 20hz, the relative power required to make the 20hz audible to an equivalent volume is exponentially higher than to make 200hz audible. That can often be the case, but it isn't necessarily always the case. There is nothing in particular that absolutely prevents a transducer from having reasonably-flat (in an amplitude-vs-power sense) response in the bass region -- including all the way down to 20Hz or below.