Please Help me help my KENWOOD amp !!!?

I've got a kac-7205 kenwood amp. It does a decent job but not quite what I was expecting. My problem is I dont really understand how the LPF "switch" and the LPF "dial" works. The switch has only OFF & LPF on it. The dial has Hz. from 50 - 200. The manual reads "The Filter switch outputs lower frequency's than the freqency set with the LPF frequency control, the Output automatical is switched to MONO (L + R) ". Dose this mean one Filter canel's out the other ? Is it possible to use both the switch and the dial? I dont understand why kenwood put two LPF's on one amp? And last but not least, The dial from 50hz. to 200hz. Dose setting it at 200Hz. get me more bass or at 50Hz.? Can anyone explain any of this to me? thanks for helping out !!!