The Bose QuietComfort 25 were released in 2015 and you can still buy them today. They are kind of like a wired version of the Bose QuietComfort 35. They have a slightly dated look, and boast almost as good levels of active noise-cancellation and sound quality as Bose’s QuietComfort 35. The important thing to remember is that even though these are wired headphones, they still need to be charged so you can turn on the active noise cancellation. Otherwise, they just work as normal over-ear headphones.
The tech-speak description for this type of headphone is "circumaural," which includes any headphones with earcups that fully enclose your ears. Because of their size and their acoustic isolation, full-size headphones are often considered to be better-suited to home use rather than as a portable option, but the recent popularity of full-size, noise-canceling Beats headphones are challenging the rule.
In early powered radios, the headphone was part of the vacuum tube's plate circuit and carried dangerous voltages. It was normally connected directly to the positive high voltage battery terminal, and the other battery terminal was securely grounded. The use of bare electrical connections meant that users could be shocked if they touched the bare headphone connections while adjusting an uncomfortable headset.
Wireless and truly wireless: These connect to your devices using Bluetooth, so you’re never physically tethered to your smartphone, tablet, or computer. Wireless headphones don’t use a wire to connect to an audio source, but they do use a wire to connect the two earpieces together. In contrast, “truly” wireless headphones come as two separate earpieces that don’t need wires to connect to anything. Wireless headphones are incredibly affordable; truly wireless headphones can cost anywhere from $100 to $400.
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.
Released in 2017, the Bose SoundWear Companion is a different kind of wireless headset. It doesn’t have any earcups or earbuds, but instead it sits around your neck adn has speakers that shoot sound up towards your ear — it’s essentially a portable speaker that sits around your neck. It’s water-resistant, so you can technically work out while wearing it, but it’s really designed for the person who works at home. It’s comfortable enough to wear for lengthy periods of time, but it also has excellent built-in microphones and works great as a speakerphone.
The impedance of headphones is of concern because of the output limitations of amplifiers. A modern pair of headphones is driven by an amplifier, with lower impedance headphones presenting a larger load. Amplifiers are not ideal; they also have some output impedance that limits the amount of power they can provide. To ensure an even frequency response, adequate damping factor, and undistorted sound, an amplifier should have an output impedance less than 1/8 that of the headphones it is driving (and ideally, as low as possible). If output impedance is large compared to the impedance of the headphones, significantly higher distortion is present.[11] Therefore, lower impedance headphones tend to be louder and more efficient, but also demand a more capable amplifier. Higher impedance headphones are more tolerant of amplifier limitations, but produce less volume for a given output level.
At the heart of the WH-1000xM3 is outstanding wireless sound. Sony’s LDAC technology delivers a wireless signal at what the company claims is three times the quality of standard Bluetooth streaming, and the headphones also support the latest aptX HD codec (with supported devices). The 1000xM3 even “upscale” wireless music from high-resolution audio devices using a special chip, helping to make music sound dynamic and beautiful, with authoritative bass and clear treble response held together by a well-rounded midrange.
Garbage in = Garbage out (GIGO) is a popular phrase used to emphasize the importance of a good source. This can be the soundcard in your laptop, the quality of your portable audio player, or the CD player you’re using for music listening. Those fall into the “Source” category. The better your source is, the better the sound will be at the headphone end. This is why we are seeing more and more audiophile digital audio players (audiophile DAPs). They are expensive but they sound good.
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?
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.
The SoundSport Wireless are wireless sport earbuds that are very similar to the SoundSport Free. Instead of being true wireless earbuds, however, the two SoundSport Wireless earbuds are tethered together by cable. Aside from that, the two wireless earbuds have similar audio performance and use the same Bose Connect app. The SoundSport Wireless will last longer on a single charge (as opposed to the SoundSport Free which recharge every time they go back in their case).

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:

Although modern headphones have been particularly widely sold and used for listening to stereo recordings since the release of the Walkman, there is subjective debate regarding the nature of their reproduction of stereo sound. Stereo recordings represent the position of horizontal depth cues (stereo separation) via volume and phase differences of the sound in question between the two channels. When the sounds from two speakers mix, they create the phase difference the brain uses to locate direction. Through most headphones, because the right and left channels do not combine in this manner, the illusion of the phantom center can be perceived as lost. Hard panned sounds are also heard only in one ear rather than from one side.

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.
Technology has changed our lives in some pretty big ways – nowadays, it’s hard to imagine leaving the house without at least a few of our most important gadgets. New tech categories are sprouting up out of nowhere; ten years ago, no one had ever heard of a smartwatch, and now you see them everywhere you go. But there’s one tech category that’s remained essential all along: headphones.
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.
They’re among the best-performing wireless home/studio-style headphones in our ratings, and though the price fluctuates, you can often find them for as little as $150. That’s less than half of what you’d pay for some comparable models. If you want over-ear headphones with the convenience of Bluetooth, this pair is a steal. It comes with a detachable audio cable so that you can use your headphones without draining the battery, and the ear cups fold in for easy storage and travel.
Wired headphones are attached to an audio source by a cable. The most common connectors are 6.35 mm (¼″) and 3.5 mm phone connectors. The larger 6.35 mm connector is more common on fixed location home or professional equipment. The 3.5 mm connector remains the most widely used connector for portable application today. Adapters are available for converting between 6.35 mm and 3.5 mm devices.