heres the gear i'm currently hooking up: OLP musicman 4 string gallien krueger backline 600 fender bassman 1x15 the head has 2 channels, one has gain and the other is clean. theres a 10db pad, which i usually use because i play very hard and sometimes the bass will clip the input. however, when i'm playing live (usually i add a 2x10 to the combination, which brings it down to 4ohms which the amp is rated at) i need the extra volume so i don't use it. the clipping isn't a problem because i usually crank the boost and midrange so it is a real dirty overdrive sound. but the other night at a show i couldn't use it at all, no matter what i did to the EQ the output from the amp was just 100% bass and no treble. i worried about blowing out my speakers since it was SO bass heavy, so i borrowed a friends 4x10 combo and played the rest of our set with that. **** was embarassing. anyway, i took it home to listen, and without the pad on the clean channel is distorting heavily and theres a bit of a phasey/comb filter style effect you can hear. what would cause this? the amp is only from december.