Some years back, I was living in a house at the top of a hill at the edge of a deep and wide valley. When a thunderstorm rolled in, you'd really know it -- and it tended to stick around. One not so fine day, a storm was a-comin', so I unplugged everything. Everything. And when the house got hit by lightning -- YOIKES!!! -- it still cooked the amp and one of the speakers. (The amp sat on the floor between the speakers on one wall while the sources and the preamp were on another wall. A pair of interconnects that were maybe 15 feet long connected the pre to the power. Apparently, when the house was struck, everything (the walls?) got charged enough to spark the interconnects enough to fry something in the amp, which in turn blew out a speaker. So now I leave everything plubbed in and turned on all the time. Unless I hear a thunder storm a-comin', of course.
