Part of the linked article below is, frankly, gibberish to me. It's so technical and I don't know the machines they talk about well enough to completely understand it. Your mileage may vary, but it does prompt one question: it talks about a gadget called a Bolin Phase Box, which the author claims can "phase out" local FM signals to allow more distant channels on the same or adjacent frequencies come in better during a DX event. 

Has anyone ever heard of this and does it actually do what it seems to promise? It would be amazing to be able to 'null' out a local signal in order to see what, if anything, is behind it. But I just don't see how it could really work. 

Seasoned DXer Shares Tips for FM Radio Phasing