2000 Sentra GXE radio backlight problem

Whenever i turn on the headlights on, the radio display goes dark. When i turn off the headlights, the radio display lights up perfectly. This on the stock radio. All the fuses are fine (engine & passenger compartments). Any ideas what to check next? I am tempted to just replace it with an aftermarket unit. That should be cheaper than taking it in to have it checked.