I have a pair of Behringer HPS3000 headphones, which work normally when plugged in to the amp with their own cord, but the right one stops working when I plug them in to my laptop, speakers or iPhone using a connector. I'm pretty sure it's not a problem with the connector, as my guitar worked fine when I would use the same connector to plug it in to my laptop.Any ideas what I could do?
It IS the connector. Your guitar is a mono source, while your other sources are stereo. It's probably a mono adaptor. Easy to tell, though: If it has one black insulating ring on the shaft of the plug, it's mono. If it has two, it's stereo.