So many things make a headphone good or bad for metal detecting
1. Comfort - both initially and after 6 hrs
2. Sound isolation - wind noise, the scraping of your coil, walking etc all distract you from hearing faint signals
3. Robustness - self explanatory
4. Length of cable - too long and it's a pain, too short and you can't use it on all detectors
5. Stiffness of curls - too stiff and it will put strain on connections, too soft and it will soon stretch and become sloppy
6. Frequency response curve - any audio output device will have a response curve. Headphones for dj'ing will have a pronounced bass, and a little bit of top end boost. Gaming headphones have massive bass, very crispy top end, and a bit of a virtual surround sound about them. Studio headphones try to be quite flat, i.e. a natural response. Multi-tone detectors like the CTX3030 work very well with these studio type headphones, as you get equal loudness on the range of frequencies. For most gold detectors, the response is very focused on the mid-range frequencies, so headphones with a very clear and transparent mid range and preferably a roll off on bass and high end frequencies will really help you to hear faint signals. The two headphones I've tried that fit this model are the Koss TD80's and Sunray Pro Gold's. The technics rpdh1200s you may have seen in a few of my YouTube videos have awesome sound, but these day's I'm using the Sunray Pro Gold's 90% of the time as they tick all the boxes.