Kurt,
I noticed that the JBL subs used today for cinema sound go down to about 25hz. Do you think that these subs might not be delivering all there is? I am just curious about it. Also, I did download a frequency generator, and discovered, I've got to really pump up the volume to hear or feel anything below about 50hz. And, yes, my sub does seem to improve the dynamics of my music, especially dance music like Kayne West's Love Lockdown.