I don't think that anyone can "hear" 5 Hz but you will be able to feel it. Here is my question, how many sountracks have LFE material that goes down to the 5 Hz range?
+1 jcPanny... No-one can hear 5 Hz, you could only feel it, and exactly whats the point when there is nothing recorded that low...
Now I can see the new SVS Ultra starting to hit numbers in the low teens with 10Hz tuning... cool, I would love to feel that...
I love the thought of having a sub that will disturb my innards...
But 20K... busy..