Tim,
Before you rush out and spend $100 plus for headphones that you might not need, why don't you give the stock ones a chance? I use them with the Sunray adaptor, and they work just fine for me and a lot of other people. My only criticism is that the ear pads are a touch small for me, and after a few hours, the edges of my ears sometimes start to tingle. If I do get another set, it will be for this reason, not because they do not reproduce sounds adequately. And don't be mislead into believing that if 32 ohms of impedance is great, 90 is better and, wow, 150 must be the cats meow. Efficiency is maximized and distortion is minimized when the impedance of the receiving unit (headphones) matches the impedance of the output stage of the transmitter (your metal detector). There is no way an aftermarket set manufactured with one fixed impedance value can work better with ALL brands of metal detectors that get designed to accept various input impedances levels because there is no one "standard" value. They make look better, feel better, last better, but not necessarily sound better (volume, clarity) than the stock ones. That's why it's a good idea to find a local dealer who will let you try before you buy.