If you're planning to use your headphones with a home theatre system or a gaming rig, you might want to consider headphones that support surround sound. These days there are several brands with models that support 5.1 playback as well as the older 4 channel gaming configuration. Because 5.1 incorporates multiple channels, it can be a good idea to look for a model that lets you adjust the mix between the front, centre and rear channels.
If you're not concerned about surround sound, but still want a pair of headphones that are good for lounge-room movies, TV and music, look for something with large cups that completely cover the ears. These will block out sounds from outside as well as minimise the noise they create in the room around you. You may need a long cable to reach the headphones output of your amplifier, however, and coiled cables are the best way to minimise knots and mess, but make sure they are long enough. Most cables are 2-3 metres in length, but measure up the room beforehand.
Headphone cables can either be connected to one side or the cable can be "Y split" with a wire going into each cup. Avoid the split cable type as you will inevitably become entangled in it on a regular basis. While a long cable will give you the flexibility to move away from the source of the audio, it's worth bearing in mind that cable length can impact the sound quality, both by lowering the overall volume level and introducing noise. Quality headphones will come with shielded cable to prevent handling noise and, if you need more than 3 metres of cable, you will probably need to buy an extension. If you are buying a quality pair of headphones, be sure to get a quality extension cable as well. Some models let you replace the cable with a longer one instead. This is a feature lacking even in some top quality pro headphones, but it's worth paying a little extra for. If your cable gets sliced or the plug gets bent, it's cheaper to buy an expensive cable than an ordinary pair of replacement headphones. The same goes for cups as well, if you're spending several hundred dollars, find out if the parts are replaceable.
Some headphones are louder than others. This is often because the speaker drivers have higher sensitivity, meaning they require less amplification power. Many DJ headphones are designed with high sensitivity and incorporate bass and treble boosts as well. This can make it easier to mix music in a loud environment, but it doesn't necessarily lend itself well to listening enjoyment. Portable headphones will require a sensitivity rating of at least 100dB, while most others can get away with 90dB or less. The other specification that's worth comparing is the impedance of the speaker drivers. The lower the impedance, the less power that is required to drive the speaker and, as a result, the more volume you will get out of it. Portable headphones should have less than 64ohms whereas anything up to 100ohms is fine for most other uses. Occasionally you will find models which have volume controls mounted on the cups or along the cable. While the added convenience may be appealing, it is better to avoid inline volume controls as these can be a source of noise and, as they involve moving parts, they have a tendency to be the first things to break.