What’s a Headphone Amp, and Why Would You Need One?

Most modern headphone amps also include an electronic component called a DAC (digital-to-analog converter). A DAC’s job is to convert digital audio information into a low-voltage signal that an amplifier can, well, amplify.

Analog components like a turntable or tape deck don’t need a DAC – they already put out analog low-voltage signals — but digital audio devices like PCs, smartphones, iPods, or tablets need both a DAC and headphone amp in order for you to hear sound through your headphones.

All those digital devices we just mentioned already have a DAC and headphone amp built right in — that’s why you can just plug your headphones in and hear sound. Why, then, would you need a separate component?

Unfortunately, the quality of those built-in components varies greatly from device to device, and therefore, so does the sound quality. A MacBook Pro has a decent DAC and headphone amp built-in, so it sounds … decent … but many laptops, like the old Dell Inspiron N5110, for example, have very low-quality DACs and headphone amps, so they sound pretty bad. The same goes for phones: Some sound terrible, some are decent, and some — like the LG V60 ThinQ — sound superb.

Frankly, if you don’t have a good-quality pair of headphones (read: better than a pair of $30 earbuds), you won’t benefit from a headphone amp. But as the quality of headphones increases, so does the potential benefit of using a headphone amp.

Does anyone need a headphone amp? That’s questionable. But might you want one? If you dig great sound, the answer is a resounding yes.

There are also certain kinds of headphones that really do need a headphone amp to function properly: We call these high-impedance headphones. Impedance refers to the resistance of an electrical signal, and is measured in ohms — the higher the impedance, the more resistance a pair of headphones or speakers will give to an electrical signal.

For headphones, impedance can vary widely, from around 16 ohms on the low end to as high as around 600 ohms. Generally, the higher the impedance, the more amplification power is needed to drive the headphones, and the more likely a headphone amp would be beneficial. If you’re curious about the impedance on a pair of headphones, you’ll find it in the manual or specs section online.

Classic headphones like the high-end Sennheiser HD800 (300 ohms) and the cheaper but renowned Beyerdynamic DT990 (600 ohms) were originally designed for use in listening rooms and recording studios with powerful audio gear. Therefore, a headphone amplifier with more voltage than what’s available inside the average smartphone is needed to get these headphones to play at desired volume levels and perform properly. Modern designs such as Audeze’s LCD-3 (110 ohms) and LCD-4 (200 ohms), which use planar magnetic drivers instead of more traditional dynamic drivers, also require the power of a dedicated amp for optimal performance.

Not all high-performance headphones are high-impedance, power-hungry monsters, though. As our audio sources have gotten smaller, headphone designers have adjusted. New technology makes high-performance headphones with low impedance possible, and these work well with low-power devices. Philip’s SHP9500 and the previously mentioned Beyerdynamic DT990 are great examples.

Most in-ear headphones — which naturally utilize smaller drivers that require lower voltage — also generally work fine with portable devices.

While there are no hard or fast rules, if your headphones have an impedance of, say, 50 ohms or higher, a headphone amplifier is probably a good idea — we would consider you to be in the need camp.  If your cans are below 32 ohms, they’ll work fine with virtually any consumer audio device. With that said, you could still be in the want camp.

Most commonly referenced in professional audio circles, the signal path — or signal chain — refers to any and all components that make contact with your audio signal. In our case, that likely includes a digital source, DAC, amplifier, a pair of headphones, and finally, your ears. The higher the signal-path quality is, the higher the sound quality will be. Though you can’t replace the last stop on the list (yet), the rest are all in play.

You may have landed here to learn about headphone amplification, but we’d be remiss if we didn’t point out that the DAC is an extremely important stop on the good train audiophile. The DAC is a critical portal between you and your sound because it changes the sound data from digital information — simple code consisting of 1s and 0s — into electrical current. The better that transference point, the better the sound.

Quality amplification can also improve sound quality for virtually any pair of headphones from around the $100 price point up; basically, any model built for sound quality over colorways and cute designs. When matched up with a good pair of headphones (and a good DAC), quality amplification can do some very cool things. It can lend more or less color to the sound as desired. It can make the sound clearer and more balanced, or on the other end, warmer, richer, and smoother. A good headphone amplifier can also affect the sound in other ways, including isolating the current running inside the device to limit crosstalk (interference between stereo channels), which can muddy up the end product.

The best amplifiers and DAC solutions create a purer, clearer, and less distorted signal. The better the signal that reaches your headphones, the better your sonic experience will be.

OK, so you’ve decided to pony up and buy yourself a dedicated amplifier or amplifier/DAC combo. That means it’s time to cash out that Apple stock, right? Not necessarily. There are a number of ways to up your headphone game, at a number of price points. We’ll go through a few to help get you started.

There are a wide variety of quality mobile headphone amp/DACs to choose from. On the high end (though they go much higher) are products like Shure’s excellent SHA900, which can push virtually any pair of headphones you can find (up to 600 ohms), offers versatile input connection and four-band parametric equalization, and high-resolution digital audio support at up to 24-bit/96kHz. If the $1,000 asking price is too rich for your blood, there are also much more affordable options like the $60 FiiO A3, which gets high marks from reviewers and can push headphones from 16-150 ohms.

A relative newcomer to the headphone amp game, the USB DAC/headphone amp or DAC stick is one of the easiest ways to improve the sound directly from your computer’s USB output. While they require a laptop to take them on the road, they represent a supremely simple and affordable way to raise your signal-chain game. Our favorite at present is the DragonFly Red, which costs $200 and is claimed to be able to drive virtually any pair of headphones you can throw at it, even the “lowest efficiency” models like those referenced above. There’s also the DragonFly Black ($100) for your medium- to low-impedance cans. Another option we like is the Cambridge Audio DACMagic XS, which will also run you around $100 or less.

The desktop headphone amp is a staple in the industry that should not be overlooked. While often pricey and bulky, these devices are anything but out of date or style for true audio fans, and many represent the absolute best way to take your daily audio to the next level. There are far too many types to outline here, but we’ll go over a couple of solutions that stand among our favorites at the moment.

Our previous choice, the Oppo HA-1, offered a healthy blend of digital and analog features for incredible functionality. Unfortunately, it’s no longer available (unless you can find it used), as the company went belly-up. Luckily, there are plenty of other top contenders on the market. One great option is the RME ADI-2. Built from the ground up as a formidable DAC and headphone amp, the ADI-2 comes loaded with digital optical and coaxial outputs, analog RCA outputs, an onboard Line Out EQ monitor, and an Extreme Power headphone output for delivering the ADI-2’s ultra-refined signal directly to your favorite audiophile headphones.

Our other pick is the decidedly old-school cool Kenzie tube headphone amp from Amps and Sound. Those glowing tubes on the top will pull in plenty of admirers, while also perfectly outlining our point about sound coloration. Illustrating our previous point about colorization, where the Heritage amp is fizzy and vibrant, the Kenzie is warmer, richer, and smoother. One of the few options on our list that isn’t a DAC/amplifier combo, the Kenzie sources analog sound from your preferred output, and is therefore dependent upon your DAC. The sound is also a shade noisier than more modern amps, including the Heritage. Even when connected to a basic headphone output, though, the Kenzie brings magic to your mix, and should get serious consideration from those with a great pair of over-ears.

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