I would think that some defective equipment in the neighborhood was generating electrical noise. With the power outages, it finally failed.
In the past, I could hear a distant mechanical noise, after a wide area power outage, the noise was gone.
It started as a fun DIY project in 2013.
Fancy Interconnects? How about a potato, or even mud?
https://www.diyaudio.com/community/threads/fancy-interconnects-how-about-a-potato-or-even-mud.236248/
Then was revived in 2024.
Copper wire vs bananas vs mud - An interconnect test...
It's a dim bulb starter. It limits turn-on AC current. It allows old power supply capacitors to re-form slowly.
Also in components that have a serious problem, it prevents blowing the power supply fuses.
Does it buzz 24 by 7 all year or just at certain times?
In a residential neighborhood, there is not much that can cause a continuous DC offset.
Also check the AC line voltage. Some toroidal transformers are sensitive to high line voltage.
(most DC blockers reduce the line voltage a bit)
As above: Turntables and speakers certainly.
Components with moving parts like CD/DVD players, hard drives or fans, often true.
Placed over other components with big power transformers, maybe.
Three thoughts:
1) You can have the electric power company install a whole house surge suppressor in the meter base.
2) MOV's have come a long way in the last half century. Those horror stories are old news.
3) retracted