Unlike regular headphones, which are designed for overall music quality and a balanced listening experience, the units designed for the Dj market are slightly different.
Used for monitoring of the yet unplayed or unmixed audio source, the Dj headphone often finds itself being held in awkward positions, held up to one ear, rested on a shoulder, hung around the neck, or over the head but with one side behind the ear on the back of the head. So one of the most important design factors is the joint mechanism between headband and earcup, how flexible it is, and that it will stay in the position you want it to.
Weight is also a factor, as heavier headphones will slip off unless you're wearing them completely over the head.
There are budget options available, which are designed for lower volume environments and less physical robustness, which is perfect for the casual home user or hobby Dj.
These will generally have smaller drive units, and plastic body construction. They are still designed for purpose though, so are still a preferable option over using normal audio headphones as they are shaped differently and are frequency adjusted to enhance quiet signals.
Frequency enhancement is an important design factor in headphones. In a pair of studio monitors for example, they are designed to be as flat response as possible, so you can hear any issues with the recording, jumps in volume etc. This differs from the ‘hi-fi’ type of standard headphone on sale, which are designed to enhance the lower midrange and upper treble frequencies, as that is what sounds most satisfying to human hearing when listening to music.
Dj headphones on the other hand are designed more for specific sounds rather than music, and are engineered to make the top end and low end stand out much more prominently than standard headphones do, as this makes beat matching and timing much easier, and also allows the actual overall volume level to be lower at the same time, so you're not blasting your hearing in trying to make out a bassline.
The drivers are also made physically tougher than standard types, in order to cope with sudden loud jumps or stabs in volume from the source audio.
To help with these enhancements, monitor headphones in the medium to higher cost brackets will use 40mm or larger drive units, generally with closed back designs to decrease loss and increase the SPL, and often have aluminium or composite construction for added rigidity and higher overall build quality.
No matter the cost, design, or brand, all headphones use the industry standard jack plug connections of either 3.5mm or the larger 6.35mm (¼ inch), and each can be easily converted to fit the other using the appropriate adaptor, so you never have to worry about any compatibility issues whatever you choose. This does also mean that they can be used daily, on your ipod or phone if you so wish, though that is not what they were designed for, and use of large driver sized monitor headphones on a battery powered source will considerably drain that devices battery life.