Hi mate, I've seen your movies just now. It seems that the relay-protection is having a latency when you power up the BANG. Either the internal circuit that powers up the relay, either a defective relay could cause this. Internal noise is caused by this relay, same noise you're hearing into the speakers is also caused by the same relay (imperfect contacts inside the relay. This unit needs to get replaced; mine is not doing so.

P.S.: I wonder if the power brick is perfect or not; when BANG powers ON it draws a huge amount of current, especially if 4 Ohms speakers are connected (is the internal relay noise still present if no speakers are connected?). If you can borrow another BANG power brick might help in finding the right answer. Thanks!

Hey @raoultrifan, thank you for your feedback! I did send this review to Burson, but would not be surprised if they didn't watch. The first of the two videos is without connected speakers, the second is with 6 ohm speakers. I am also experiencing it into my 4 ohm speakers.

I would not be at all surprised if the power brick is defective since it's from the same manufacturer that made the defective Fun PSU I had. And Burson said it was that PSU that damaged the PCB in that unit.
I could bring it up with Burson support, maybe they concur. That would be the third PCB surgery I'll have to perform, haha. Oh, well.
Thanks again!

Perhaps your home is haunted? Kind of strange to get so many bad PSU after all. I do hope you'll find a resolution to this.
Do you have other SMPS powered devices in there that got defective in the past? I know my home has about 12-14V more than it should be, but no damage in the past few years because of that.