I've kept voltage meter on home ac for years. This after I was having issues with transformers in several audio components humming and buzzing. Discovered I had consistent 125v on ac lines, had to build bucking transformer to shelve down AC to 120V. At some point power company fixed the issue, now have consistent 120V. Microwave oven and space heater I use are biggest suckers of power, microwave can drop down to 117, run microwave and heater together, can go down to 113-115. My audio system doesn't create any voltage drop. I could see how high power amps could cause power sag. Good post!
