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.
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:
Historically, many headphones had relatively high impedance, often over 500 ohms so they could operate well with high-impedance tube amplifiers. In contrast, modern transistor amplifiers can have very low output impedance, enabling lower-impedance headphones. Unfortunately, this means that older audio amplifiers or stereos often produce poor-quality output on some modern, low-impedance headphones. In this case, an external headphone amplifier may be beneficial.
Headphones connect to a signal source such as an audio amplifier, radio, CD player, portable media player, mobile phone, video game console, or electronic musical instrument, either directly using a cord, or using wireless technology such as Bluetooth, DECT or FM radio. The first headphones were developed in the late 19th century for use by telephone operators, to keep their hands free. Initially the audio quality was mediocre and a step forward was the invention of high fidelity headphones.[3]
Dirac is mainly for resonance (narrow band) taming and not suitable for normal EQ. Accudio is good. But since the L1 already has a strong bass emphasis, boosting mids or treble just makes the imbalance worse – i.e. the freq. response becomes more ragged and the sound more harsh. To get a smoother sound and better mids and treble, reduce the bass instead.
LDAC is a strange family of codecs, not merely because they’re the only codecs that really attempt the hi-res thing, but because they have perplexing issues with common phones. For example, the bitrate defaults are wildly different from phone to phone. The Samsung Galaxy Note 8 and LG V30 both default to 660kbps, and the Google Pixel 3 defaults to the lesser 330kbps. However, the noise present with every LDAC connection is far greater than it is with a regular old 3.5mm headphone jack.
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.
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.
The WH-1000xM3’s excellent noise-canceling technology ranks second only to the Bose QC35 II, from the brand that has long dominated the market in terms of sheer noise-blocking abilities. That said, the Sony cans sound much better than the new bass-forward Bose option, and offer numerous features that help to create a much better overall experience.
A headset is a headphone combined with a microphone. Headsets provide the equivalent functionality of a telephone handset with hands-free operation. Among applications for headsets, besides telephone use, are aviation, theatre or television studio intercom systems, and console or PC gaming. Headsets are made with either a single-earpiece (mono) or a double-earpiece (mono to both ears or stereo). The microphone arm of headsets is either an external microphone type where the microphone is held in front of the user's mouth, or a voicetube type where the microphone is housed in the earpiece and speech reaches it by means of a hollow tube.
The Bose Frames are non-polarized sunglasses with special speakers built into each arm. The idea is that they’re designed to look like regular sunglasses, but also act as Bluetooth headphones. Since there’s no earbud that actually goes into your ears, the speakers have been engineered to shoot audio down into your ears; the neat thing is that the Bose Frames do a very good job at masking your audio so that the people around you can’t really hear what you’re listening to. They are available in two different frame styles, round (Rondo) or square (Aldo).
Earphones are very small headphones that are fitted directly in the outer ear, facing but not inserted in the ear canal. Earphones are portable and convenient, but many people consider them uncomfortable.[16] They provide hardly any acoustic isolation and leave room for ambient noise to seep in; users may turn up the volume dangerously high to compensate, at the risk of causing hearing loss.[16][17] On the other hand, they let the user be better aware of their surroundings. Since the early days of the transistor radio, earphones have commonly been bundled with personal music devices. They are sold at times with foam pads for comfort. (The use of the term earbuds, which has been around since at least 1984, did not hit its peak until after 2001, with the success of Apple's MP3 player.[18])
Headphones may be used with stationary CD and DVD players, home theater, personal computers, or portable devices (e.g., digital audio player/MP3 player, mobile phone). Cordless headphones are not connected to their source by a cable. Instead, they receive a radio or infrared signal encoded using a radio or infrared transmission link, such as FM, Bluetooth or Wi-Fi. These are powered receiver systems, of which the headphone is only a component. Cordless headphones are used with events such as a Silent disco or Silent Gig.
The thermoacoustic effect generates sound from the audio frequency Joule heating of the conductor, an effect that is not magnetic and does not vibrate the speaker. In 2013 a carbon nanotube thin-yarn earphone based on the thermoacoustic mechanism was demonstrated by a research group in Tsinghua University.[22] The as-produced CNT thin yarn earphone has a working element called CNT thin yarn thermoacoustic chip. Such a chip is composed of a layer of CNT thin yarn array supported by the silicon wafer, and periodic grooves with certain depth are made on the wafer by micro-fabrication methods to suppress the heat leakage from the CNT yarn to the substrate.[citation needed]

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:

Alternatively, online calculators can be used.[13] Once the sensitivity per volt is known, the maximum volume for a pair of headphones can be easily calculated from the maximum amplifier output voltage. For example, for a headphone with a sensitivity of 100 dB (SPL)/V, an amplifier with an output of 1 root mean square (RMS) voltage produces a maximum volume of 100 dB.
Hi. I have more or less decided that the Philips Fidelio L1s are the ones for me. I plan to use them on my commute paired with an iPhone or the iPad as the source. I listen to a mix of pop, rock, blues and jazz so I’m not after boosting bass but I might want to fiddle with the dial on the treble and mids. Which brings me to my question. You state in your review that the L2s pair well with the Fiio e17 which lets you independently adjust treble and bass. Could the same effect be achieved lower down the $$ curve via a combination of say a Fiio E6 (for signal amplification) and a Dirac or Accudio app for equalisation?
Sealed models are ideal for private listening, where you don't want the sound to be heard by other people. Open headphones -- such as foam earpad models and many sports designs -- are acoustically transparent and allow outside sound to be heard by the headphone wearer, and a good deal of the headphones' sound will be audible to anyone near the listener.

The rule that I use is that the bigger the size of the headphone, the bigger the need for amplification. Of course factors like driver sensitivity and impedance will matter, but the general rule of thumb is, use a dedicated headphone amplifier for a full size headphone. Even a portable amplifier can be enough, depending on the type of the headphones.
Recently released this summer, the Headphones 700 are the best wireless over-ear headphones that Bose has to over. The combine the best-in-class noise-cancellation with great audio quality. Other than the design overhaul, the biggest difference from the QuietComfort 35 II is that the Headphones 700 have a significantly upgraded microphone array. This allows the headphones to have a wonderful tranparancy mode (or ambient listening mode), and makes maybe the best headphones you can buy for call quality.
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.
However, the Bose 700 earphones have a much slimmer profile when folded up, and they have a few updated elements, including more integration with digital assistants, touch controls, and sensors for Bose’s “augmented reality” apps. Bose has kept some of the best-loved features from its older models as well, such as adjustable levels of noise cancellation, a monitoring mode to let in sound from your environment, and an advertised 20-hour battery life. According to Bose, call quality is improved as well, though CR doesn’t test call quality in headphones.

We were frankly surprised at just how good the AirPods Pro turned out to be. The noise cancellation is on-par with Sony’s WH-1000XM3, which is saying a lot. The new in-ear design is both comfortable and secure. And amazingly, they sound way better than Apple’s previous version. We would often bemoan the fact that the AirPods didn’t sound very good, especially when compared to the plethora of decent true wireless options for the same or less money.
Sony’s technologically advanced WH-1000xM3 are the third generation of Sony’s flagship wireless headphones (following the excellent WH-1000xM2 and MDR-1000x models) that offer top-tier noise canceling, excellent quality wireless audio, and plush comfort. This enticing combination earned the model a rare five-star rating in our initial review, and — thanks to a few notable improvements — makes the latest version the best headphones you can buy.
The Samsung Galaxy Buds are one of the best-scoring portable Bluetooth headphones Consumer Reports has ever tested. That’s all the more impressive given their “true wireless” design, meaning the model doesn’t have a cord connecting the left earbud to the right. That’s the same design scheme popularized by Apple’s AirPods, but our testers say the Galaxy Buds sound dramatically better.
Once you’ve got that all order, to put a cherry on top it would be ideal for the amp to play nice with my laptops (PC at work, Mac at home) *and* my *iPhone* 4S.  I haven’t found a headunit that works with PCs and iDevices.  If one doesn’t exist it would be a big plus for the amp to include inputs so I can get digital sound out of my iPhone (with the Pure i20 or its ilk) and into my headphones.
Earbuds have small speakers that rest on the ear canal of the wearer. These are usually much less expensive than on-ear and over-ear headphones and reproduce the sound well. However, outside sounds, such as traffic or power tools, can get past the earbuds and interfere with your enjoyment. Earbuds also don't stay in place very well if the wearer is moving much, such as exercising. These also are lower fidelity than on-ear and over-ear headphones.