tonight at rehersal while in the middle of a song my amp seemed to get quieter like someone turned the volume down and i checked everything and all settings were correct for the set up. now i run a ampeg b4r head in to a svt 6x10 cab I was mono bridge and while jammin it lost some volume and even the guitarist noticed it . can anyone tell me what the heck happened? I had to turn the volume up higher just to cut through the mix .. now this is a 1000watt head and usually has no problem till tonight . Please help!