facepalm I had a disaster last week while recording and I'm curious if anyone has a suggestion on what went wrong. I was using the PreSonus Firestudio recording system. For inputs I had 1 bass amp, 2 guitar amps, three drum mics, and a small PA system. I was outputting from the Firestudio mixer to a PC with firewire. We had all this equiment distributed to a few different circuits in our house. So we had everything connected and then we plugged in the mixer. This is when disaster struck. There were highly visible blue sparks zapping the back of the mixer and the computer. We quickly unplugged everything. The Firewire express card on the PC was fried, and we replaced it. The mixer was also ruined, luckily we had insurance on this and got it replaced. Then disaster struck again. This time we played it extra cautious and distributed the equipent to different circuits in the house and also used surge protectors on everything. I had a moment where my foot was touching the 1/4" output line from the PA and when I touched the metal casing of the PreSonus mixer I could feel a little shock. I should've stopped there, but I thought my mind was playing games on me. We plugged everything in again, and when we turned on the mixer, there was visible smoke from not only the mixer but also the bass head and PA system. WTF?!?! The bass and PA were unusable and two of the inputs in the PreSonus were fried. Does anyone have ANY idea what could be causing this? I tested the voltages on all the outlets in the house successfully. I mentioned this to someone at a repair shop and they suggested it might be a ground loop (not sure what this means). I've just never experienced anything like this before when recording. Am I doing something wrong?