1. The presence switch behind the head seems to make it a lot brighter. Can anyone give me exact details on what is boosted? 2. The ultra-low button is supposed to boost lows and basically suck the mids out right? What about the ultra-high button? 3. The -15db input lowers my output by 15 db right? My bass is too overdriven, so I plug into it. Of course, that means a cut in volume. Say I were to boost my volume to meet the original level... would I have the same overdrive? What if I boosted each band accordingly? Can someone give me some details on it? Thanks a lot in advance.