If I'm not mistaken, the plus/2 has a native 20 hz. tune, I don't think there is a 24 hz. setting. the 16 hz. tune would be achived by plugging just one port, and it can be tuned even lower by plugging the other port. Even if you do get a sub that can hit 16 hz. unless you get the same sub as him, you won't notice the same effect, as the plus/2 is a beast and has the headroom to tune lower and still have lots of output throughout the whole frequency range.