Not sure what these are called. But I used one on my amps power cord going to a surge protector. Its a Parasound Halo A21 amp. Without the adapter the hum is rather loud from the fronts its powering. But with the adapter in the mix barely any hum. Is this a good idea or hard on the amp? Or could it cause a fire? I shut off amp every time I stop using it. What about if I go from an amp to an extension cord to the adapter to a surge protector? Thanks guys!