What exactly do you want from your earphones?
Basic features to decide on;
If your earphones would be tied up to your desktop and you won’t be using them for anything else, you should get a USB headset. Because the earphones would not be relying on your sound card’s ability to transmit sound accurately. Although, you’ll have to install drivers and add some proprietary software, a good pair of USB earphones can deliver great sound. Another option would be to get fiber-optic digital earphones if your sound card has a port.
On the other hand, if cables are not your thing and you love to walk around, get a pair of wireless earphones instead (Wi-Fi or Bluetooth, it’s up to you).
This refers to how well they keep music in and block outside noise. Sound isolation will also keep you from having to waste precious battery life or turn up the volume to hear properly. If noise cancellation is a priority, choose between earbud earphones or closed back ‘over the ear’ headphones.
Decide between earbuds or headphones.
Earbud earphones are best for people who are short on space but still want a way to listen to their music. They do not occupy a lot of space and so are much easier to carry around. These type of earphones tend to be better at sound isolation, due to the seal they provide in your ear.
Headphones are great if you enjoy putting them around your neck while you're walking from one place to another.
DJ-style headphones are Huge, bulky, awesome-looking headphones that you wear over your head. The structure lends itself to good sound containment, better sound quality and less pressure exuded on the eardrum, resulting in longer listening time and less damage to the eardrum. Those are better suited to situations where you stay still for long periods of time as they are prone to falling off, particularly if the headband is weighted.
Behind-the-neck headphones are headphones with a connecting band that goes behind the neck instead of over the top of the head. This is recommended are particularly suited for high-motion situations; for joggers or people who wear hats a lot and also for sunglasses fanatics. Besides that, there are very few things that separate them from DJ-style or "regular" headphones.
Notice if they are open-backed or closed-backed. Open headphones tend to sound more natural and not distorted, but people will hear your music and you'll hear the environment around you. They're recommended for home and tend to be more comfortable. Closed headphones isolate noise better and sound more like the music is in your head, not in the environment.
Depending on your preference, some people like closed-backed for the booming bass sound and isolation, while some prefer open-backed for the natural and precise sound.
Padding: each head phone comes with a certain amount of padding around (or on) the ears and over your head. For example, a large amount of padding around the ears can trap heat making them uncomfortable after some time. If you’re bothered by the excessive heat, either invest in central air conditioning or get a pair of headphones with padding that sits on your ear.
Another thing you might not immediately notice is how the weight of the head phones affects you. Think about how long you’ll be wearing the headphones. If you might be wearing this thing for hours, try getting something between 200 and 300 grams in weight. Anything lighter would be nice only if you feel good in them. Chances are that heavy headphones will affect the vertebrae around your neck in the long run even if you feel comfortable with them.
Most headphones will show a certain amount of sensitivity, measured in decibels (dB). This is only very important if you’re matching a pair of headphones to a particular amplifier, which is not often the case. However, if you’re curious, sensitivity determines how loud a pair of headphones will play at a certain voltage. It has little to do with sound quality.
A wider frequency range means you can hear more from the music; large ranges such 10 Hz to 25,000 Hz will often be recommended; anything within that range will be fine.
Electrical impedance is measured in ohms. They are a measure of how much resistance (“friction”) is generated when an electrical current passes through them. High-impedance headphones require more energy to generate amplified sounds. They’ll sound quieter in low-power equipment. Anything below 25 ohms will probably break your eardrums if you use a powerful amplifier. If you’re just buying one to attach to a computer or a phone, try something in the low 30s.
Larger drivers produce more bass. Smaller drivers produce higher frequencies. The larger the principal driver, the better bass you’ll hear. For intense bass, get a pair with at least a 40 mm driver.