When I plugged my head phones in they did not work. I then plugged my other head phones in and they did not work. The headphones are Koss headphones you get when you buy a Minelab detector. I plugged in an older pair of whites headphones and they worked. They all have the 1/4" jack. Does anyone know what the problem is?????? I like the Koss headphones and want to keep using them. Does anyone have any ideas of what is going on????