Not without a real reason necessarily. I mean you may not be able to hear sub 20hz (most people can't hear below 30, especially as the age group gets older), but you can definitely feel it. The feeling of the lower frequencies can add a lot to the music, because it can add the real "boom" to certain things like cannon fire (used in on some classical concerts before you ask). Though I've never built a system sub 20hz (my current system peaks around 44hz and dips way down in the 30's) myself, I've heard a lower and they are really amazing. Just don't get going on kimber cables...