Agreed that you can shortchange your high priced receiver if you have a lousy antenna. And also true that a poor receiver can hear things with an excellent antenna. But ultimately, when all things are equal, and depending on what your reception target is, the design of the receiver (selectivity and dynamic range are of particular interest, though other factors are important as well) can make a big difference. A cheap receiver will often overload in the presence of those big international broadcasters. and/or be susceptible to a lot of splattering due to lack of selectivity. When I was more into SWL'ing, my main target were regional and local stations in Africa, South America, Asia and the Pacific. So not only did I need a good antenna, but I also needed an excellent receiver to be more successful. I QSL'd Radio Cook Islands when they were on shortwave and running 500 watts (received in southern Indiana) back in the 70s. They weren't booming in obviously, but without a good receiver I would never have heard them in the 25 meter band amongst those big broadcasters. You don't have to break the bank buying a receiver, but if you want to DX smaller targets, it really helps to have the equipment to dig them out.