I have one neighbor, about 100 yards away. He has an outdoor bluetooth speaker that is always powered up. The switching power supply was creating tremendous buzzsaw style RFI. I bought him a nice power supply with a transformer in it and that solved the problem. The power supply probably cost more than the speaker. The speaker itself is emitting a somewhat low level screaming sound between about 3 and 21 mhz. I also hear it on FM broadcast band. I'm guessing that the RFI is being introduced into the power lines. I have a big core of type J material, I was thinking of trying to make a choke with an extension cord to plug the power supply into. Any other ideas? Thanks.