My audio engineer feels that it was a current spike that shorted one of my tubes, and so after 55 years I finally caved in and bought a Furman power conditioner from Crutchfield, on sale from $1000 down to $599.
It provides a “current reservoir” of an extra 45 amps for the amplifiers and that has made a big difference with regard to the texture, detail and authority at the bass end.
So that seems a worthwhile investment.
I still use chain-link fence for my cable interconnects.