Last night at the start of band practice, I turned on my peavey t-max and it immediately started making these weird grumbling noises that almost drowned out the sound of my bass, and the speakers were moving around an awful lot. Changing between the two channels didn't affect it at all. It did stop when we tried deactivating the active switch but this may have been coincidental. It then randomly started up again and stopped when I pushed all of the eq sliders down. It didn't do it again for the rest of the evening, but I'm hoping this isn't a sign of serious trouble. Has this happened to anyone else? Is my amp going to die?