With a Lightning a USB-C headphone you plug the headphone directly into the Lightning port (on Apple devices) or USB-C port (on Android devices). A standard headphone plug is an analog connection while this creates a direct digital connection. The headphones are powered by your phone (they use only a little bit of battery power) and have an integrated DAC (digital-to-analog converter) that's usually superior to the DAC in your phone.

Digital assistant compatibility: These days, it’s kind of a rite of passage for any tech gear to be compatible with voice-controlled digital assistants, and headphones are no exception. Certain high-end headphones include a microphone that you can use with voice commands to conjure up your favorite digital assistant, but you’ll need to make sure your smartphone is compatible. For example, if you own a Samsung Galaxy S8 phone (or newer version), you can use certain headphones to execute specific voice commands on your phone, such as “Check weather.”
The Soundsport Free, released in the fall of 2017, are Bose’s first truly wireless earbuds. They utilize the same StayHear+ Sport tips as the company’s other in-ear headphones, making them naturally more sweat-resistant and more secure than AirPods. They work with the Bose Connect app, which is pretty basic but does have a “Find My Buds” feature that, when enabled, can help you find your earbuds should you misplace them.
With a battery that’s rated for 15 hours of continuous use, we’re seriously hoping you don’t outlast them. If you do play for super extended periods, however, you’ll be glad that the earcups can comfortably rotate, giving you the option to drop the headband around your neck and still hear all the action. The latest version of the A50 offer significant customization options through software, and if you’re using them with a PC, you can connect directly to your sound card instead of using the optical connection. On the Xbox One version, you’ll even get Dolby Atmos for Headphones compatibility.
EQ controls: Equalization, more commonly referred to as EQ, controls the different aspects of sound that come through your headphones, and some headphones come with custom apps that let you adjust the EQ in granular detail. With the right EQ controls, you can add more treble, bump up the bass, or just create a sound profile that’s suited to your tastes. If you’re into customizing how your music sounds, look for headphones that work with an EQ app.
If you just want to block out sound without active noise cancellation, good over-ear headphones will naturally do that to some extent. This is called noise isolation, and it simply works from the earcups forming a good seal over your ears to prevent outside noise from getting in. It's not as effective, but it's less expensive than active noise cancellation and doesn't require power.
Headphones (or head-phones in the early days of telephony and radio) traditionally refer to a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear. Headphones are also known as earspeakers, earphones[1] or, colloquially, cans.[2] Circumaural ('around the ear') and supra-aural ('over the ear') headphones use a band over the top of the head to hold the speakers in place. Another type, known as earbuds or earpieces[1] consist of individual units that plug into the user's ear canal. A third type are bone conduction headphones, which typically wrap around the back of the head and rest in front of the ear canal, leaving the ear canal open. In the context of telecommunication, a headset is a combination of headphone and microphone.

Sensitivity is a measure of how effectively an earpiece converts an incoming electrical signal into an audible sound. It thus indicates how loud the headphones are for a given electrical drive level. It can be measured in decibels of sound pressure level per milliwatt (dB (SPL)/mW) or decibels of sound pressure level per volt (dB (SPL) / V).[12] Unfortunately, both definitions are widely used, often interchangeably. As the output voltage (but not power) of a headphone amplifier is essentially constant for most common headphones, dB/mW is often more useful if converted into dB/V using Ohm's law:

The iPhone will drive the headphone fine and make a very nice sound, but the amp will make a big improvement in harmonic extension and soundstage. Use the amp whenever possible. Both Headfonia and I concur that the E07k is a great amp, and probably the best thing you can get for up to twice the price. I’m familiar only with the E07k, the E17, and the E12. I think the E07k beats the E17 (and both are also USB DACs), while the E12 is just an amp, and has a darker sound but with more power for inefficient headphones. The Philips is not inefficient.
Portability can mean many things, such as appearance in public, having a secure fit so the headphone doesn’t shift off of your ears, amount of isolation from ambient noise (including active noise canceling), whether the headphone can be worn around the neck when not listening or it requires a carry case, and when extra amplification is required, whether a suitable amp can be found that’s OK to carry along with the portable music player.
These headphones rest on top of your outer ears and run the gamut from inexpensive portables to high-end home models. While on-ear headphones can have closed designs that cover the ears, some prefer fully sealed circumaural models (see below) for their increased sound isolation and the fact that they won't leak sound to neighbors. Still, the earpad headphone is preferred in places like office environments, where users still benefit from hearing the outside world.

The usual way of limiting sound volume on devices driving headphones is by limiting output power. This has the additional undesirable effect of being dependent of the efficiency of the headphones; a device producing the maximum allowed power may not produce adequate volume when paired with low-efficiency, high-impedance equipment, while the same amount of power can reach dangerous levels with very efficient earphones.

Ok, it’s been a month and a lot of new experience. I’ve auditoned ATH M-50 (clamp’s too tight; they sweat my ears just from few minutes of exposure) and Senn HD 600 (the velour pad is amazingly comfortable & size is ok). So, long story short, now I can refine my search to: circumaural&non-pleather/foam pads, which brought me to Senn HD 439 (cloth) & 518 (velour).
Gaming headsets are headphones that have a microphone attached and allow users to speak to other people and hear them with the same device. In fact, gaming headsets have other practical applications as well. You can use them in business or personal situations when you want to speak to people on a computer using a video phone program or social media chat room. Although these work for music applications, they're more suited for conversational clarity.