We have a sound system in the church gym that we open to the public. It's wiring has been tampered with before by one of the volunteers that helps out. He moved one of the stero wires and when I plugged my mp3 cd player up to it unknowingly, it burned out the head phone input. The board is now fine and I use it with a crappy CD player that skips too much. Now before I plug up anymore semi expensive sound input devices up to the sound board, I was wondering is there anyway to protect the device, like a surge protector. I thought about converting the 3.5mm to RCA and buying a surge protector with RCA input, then converting it back again to plug into the system. I just want to have peace of mind before I plug my MP3 player up that its headphone jack won't get burned up too. Any suggestions on how to accomplish this, with out having to spend a lot of money?