I got the professional skill with 辣雞..My first job was with Hewlett Packard, mini computer division, after college..deal with that everyday. I starting using 辣雞 at 11 years old, while learning electronics in Hong Kong. It is the easy part lol...of DIY stereo.
I used to make my own circuit board when young, played with acid and things lol...hurt my skin at times lol... Hardly 辣屎靚版, lol..
For tube gears, often didn't even need circuit boards, if simple.
Been thinking of building something small for bedroom..lol...maybe LM3866 based. Still got a pair of Visonik speakers in storage room...nice German antique speakers for bed room lol...