I have never quite figured out the crossover control on my 6x10 cab. It's labeled "horn level" and is marked 0 to 100, in increments of two. I believe I was told at one time that this is sort of a "volume control" for the horns. First of all, what measurement are these increments in? Second, how exactly might this thing work? If I set the dial at a specific number, is everything above that number directed to the horns?