Are manufacturers using these days for building amps, integrated amps, etc? I remember at some point a few years ago I heard that companies were being required to use lead free solder which was considered problematic at the time. What happened, are amps still using tin/ lead or something else inferior?

Well, after 5 days I'm reduced to asking AI for the answer. It says yes, lead based solder can no longer be used by manufacturers for HIFI components. It can still be used for certain items like medical devices, because it's more reliable and robust, than the lead free brittle garbage they use now. Or words to that effect. It said lead free is safer for children and the environment. I asked if there had been an epidemic of people opening their stereo covers and licking the circuit boards, to which it replied, "I'm sorry you feel that way." It did make a good faith effort to provide a good amount of information both pros and cons but I'm convinced I could detect an attitude when it realized I was a leaddite.