I built my stereo at age 12, then followed it up with a (much larger) bass amplifier for my bass guitar when I was 14, and a mixer/effects box at 15. Of course

I built my stereo at age 12, then followed it up with a (much larger) bass amplifier for my bass guitar when I was 14, and a mixer/effects box at 15. Of course they linked together, using the bass amplifier as a sub-woofer. I didn't have to deal with as high a voltage as you, just the 240V mains supply, and then the +-70V supply to the bass amp circuitry. I think kids these days are much more likely to do something digital than build things like this from discrete components.