Then I realized, then music I listen to well I don't know of any instruments that go below the 30hz.
It does really depend on what you listen to.
I wonder if the bass you feel you are missing is because of the room. That is one of the disadvantages of mains that reach really low. You do not have much flexibility in placement to make up for nulls and standing waves. It might just be that your mains are positione in such a way that there is a noticable null in the upper bass, affecting the way the kick drum sounds. There is no way to know for sure unless you do some measurements.
Personally I do not fiddle with my sub. I did my room measurements, equalized to flatten the response and set my levels to match the mains and now leave it alone. I ran the sub hot for movies when I first got it, but now that I am used to more ballanced bass, I much prefer it.
