here is my current chain... Active bass ---> MXR M87 Compressor ----> ODB-3 Distortion ----> Solid State amp I accidently unplugged the M87's power cable while adjusting things, while everything was on. The amp made a popping noise, I turned off the amp, and plugged it back in. While I plugged the power back in the M87, it turned on the ODB-3 distortion pedals light, and caused a spark at the M87's power plug. I didn't get shocked or anything, and everything is working fine. I'm just a little curious as to how this happened? and maybe if it did some damage to the pedal?