Isolating an electrical problem in my house is like herding cats. I once found a live 240 line that was just cut and curled up in the ceiling of the basement,... I was lucky I wasn't electrocuted when I tried to test whether it was live with a current detector. It sparked and set off the breaker... Have at least one shared neutral in the house too (opposite phases, so it's OK)... A lot of the wiring was done by one of the previous owners,... nothing labeled correctly, save what I've done... A real mess! There's also not a single plum wall or square corner either,... again, save what I've done myself...
So for me it's optical sound output, whenever possible.