First time I plugged it into an outlet at the hotel, I saw a slight spark and that dreaded sound

As soon as I plugged in the wall charger, it started making a sizzling, static sound

The second issue is that YES mine made the buzzing or hissing sound wether this is due to lack of quality control or overall due to how the USB adapter is designed

Runs very hot and always made a weird hissing sound before it quit.

A sound, quality piece delivered, as promised, in a timely fashion

The product makes a loud high pitched sound when plugged in no matter what outlet I use or what device I charge (Apple, Android etc)

It started to make a weird sound inside and it doesn't charge at all

I haven't notice any strange sounds, and I've never felt them get too warm

Makes a hissing sound sometimes, not that big a deal for me, but maybe for someone out there it could cause some form of irritation or headache

The rest of the time it has a loud electric sounding crackle when a cable is plugged in, and the flow of current goes in and out

When I plug more then one charging cable into the Aukey cube starts to make a static sound