"My experience is with toroidal transformers only. They're the circular ones. I had the same problem - hum coming from my amplifier's transformer (toroidal Plitron). Got an AVA HumDinger, hum is gone. Cost ~$125. I don't have any affiliation, and I don't sell anything."
But you must do your leg work and make sure you really need an AVA HumDinger or they will not sell you one... I tried to purchase one from AVA but he was not willing to sell me one. Told me to do all this other electrical work instead. I appreciate that somewhat, but at the same time, it would of worked on something in my office system and did not understand being rushed off the phone with no willingness to sell me an available product they offer. My guess is they build them as needed and AVA did not want to build one at the time... SO just make sure you need one or know how to explain your needs or you may be turned away... Or just go with the PS Audio Hum Buster.
But you must do your leg work and make sure you really need an AVA HumDinger or they will not sell you one... I tried to purchase one from AVA but he was not willing to sell me one. Told me to do all this other electrical work instead. I appreciate that somewhat, but at the same time, it would of worked on something in my office system and did not understand being rushed off the phone with no willingness to sell me an available product they offer. My guess is they build them as needed and AVA did not want to build one at the time... SO just make sure you need one or know how to explain your needs or you may be turned away... Or just go with the PS Audio Hum Buster.