Audio show exhibitors have a lot of obstacles to contend with: equipment not showing up or showing up damaged, problem with room acoustics, problems with the electrical supply, equipment malfunctioning just as the show starts, and countless others. Ian Grant of Grant Fidelity told me that when he first set up his turntable front end it was picking up the signal from a local radio station! Being an ingenious engineering-type, he located the source of the interference (he could see the station's antenna from the hotel window), and got some building insulation material that had aluminum foil as part of its construction, and taped it to the hotel window. Voilà! Problem solved!