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The rise of mobile music devices, like MP3 players, smartphones and tablets, has mostly been for the better. Today’s audiophile can store literally thousands of songs their pocket and enjoy them with just a few taps of a touchscreen.

If you’re serious about music, however, you may be disappointed by the audio quality your mobile device manages – particularly when paired with high-end headphones. The solution is to pair your mobile device with a portable headphone amplifier, a small device that can greatly improve your listening pleasure.

What’s An Amp, Anyway?

I’m sure you’ve heard the term amp before, but you may have never needed to learn about what it does. Only audiophiles working with high-end audio setups Quality Sound On The Cheap - Buying Vintage Audio Equipment Quality Sound On The Cheap - Buying Vintage Audio Equipment For the money you put in, an old amp has the potential to provide way more bang for your buck than a modern active speaker system. Read More regularly worry about details like these.

headphoneamp

Amp is, of course, short for amplifier, and the name is an accurate description of what an amp does. The amplifier increases the power of an audio source so that it can properly drive bigger, louder equipment. Home theaters Building A Home Theater System? Do It Right! 10 Crucial Mistakes To Avoid Building A Home Theater System? Do It Right! 10 Crucial Mistakes To Avoid Do an image search for "home theater" and you’ll see photo after photo of huge, lavish theaters with seating for up to twenty (or more!) and giant screens. These ideals are every tech geek’s dream,... Read More sometimes use an amplifier (usually in a receiver) to power big speakers, and bands inevitably need amps to power massive concert speakers.

A headphone amp is simply a smaller version of this same concept. The smallest are barely the size of a solid state hard drive, while the largest are around the size of CD-ROM drive, but they all accomplish the same goal.

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Why Might You Need One?

The connection between the amps which power concerts and a pair of headphones What Are Celebrity-Endorsed Headphones And Why You Should Avoid Them What Are Celebrity-Endorsed Headphones And Why You Should Avoid Them Celebrity endorsements are nothing new. There is one type of product, however, that's become notorious for its epidemic of endorsements; headphones. Read More isn’t obvious. You might think headphones easy to power, and compared to other audio equipment, that’s true. But a smartphone (or MP3 player, or tablet) is exceptionally small and must manage power usage carefully. This means some mobile devices don’t provide the power required to drive high-end equipment.

Headphones are essentially a set of speakers rigged to fit on your head and comfortably over your ears. Like all speakers, they need power, which is provided (in this situation) by a 3.5 millimeter audio jack. If the power provided by the jack is not enough to fully drive the speakers you’ll find them strangely quiet and feel that certain aspects of the experience, such as strong bass, are missing. This occurs because headphones, unlike most electronics, don’t switch off when they receive insufficient power. They work – but not as well as they could.

sennheiserhd800

The power you’ll need to drive a headphone can be inferred by its impedance. A set with high impedance (like the Sennheiser HD800, which is rated at 300 Ohms) requires more voltage to produce a given volume than those with low impedance (like the Denon AHD-2000, which is rated at 25 Ohms). You will probably benefit from a headphone amp if your headphones are rated beyond 32 Ohms, but you likely don’t need an amp unless you use a set rated at 100 Ohms or greater.

Your ears, however, should be the final judge. Those that aren’t as loud as you’d like almost certainly aren’t receiving as much power as they should. If unsure, try the same pair with a home theater receiver or other powerful audio source to see if volume improves.

Note, also, that all of this talk only applies to on-ear headphones. In-ear headphones, also know as earbuds, work differently and require far less power, so an amp isn’t needed to extract the most from them.

What About Quality?

An amplifier can increase the quality of your listening experience, but it’s not guaranteed to do so, and you may have a very difficult time telling the difference between a headphone amp and a smartphone that already provides enough power to drive your set. Tests of the iPhone 5 and other popular smartphones show portable devices work well compared to a dedicated amp – not better, but well enough for all but the pickiest audiophiles.

You’re only likely to run into an issue if the output impedance of your device is too high relative to the impedance of your headphone. In general, a device’s output impedance should be no more than 1/8th the impedance of the headphone it’s paired with. Unfortunately, determining this ratio can be difficult because most smartphone and tablet manufacturers don’t publish the audio output impedance of their devices. You’ll have to rely on audiophile reviews, when available.

I Need An Amp — What Do I Buy?

Most headphones don’t need to be amplified when used with an iPhone or other portable device. This is purposeful; headphones used to have higher impedance, on average, than they do today. Manufacturers have adjusted the way they build headphones to ensure they work reasonably well with mobile hardware.

If you’ve found you do need an amp, however, (perhaps you want to use your Sennhesier HD800s on a plane, for example) you’ll want to pick up something that’s slim yet powerful. You should aim for an amp that can provide at least 500 milliwatts of power and has as very low output impedance (preferably a couple Ohms or less).

FiiO’s E12 is a popular example. Rated at 850mW and featuring a built-in battery Extend Your Phone’s Battery Life - 3 Apps That Lead To a Longer Lasting Battery [Android] Extend Your Phone’s Battery Life - 3 Apps That Lead To a Longer Lasting Battery [Android] Have you ever forget to charge your phone overnight and, come morning, realize your phone’s battery life sucks? A portion of your troubles probably relate to Android’s inherent design flaws - in particular, its poor... Read More that can last up to six hours, this $129 amp can power virtually any headphone on the market and boasts an output impedance below 1 Ohms, yet can fit in your pocket. This is a great pick for audiophiles.

fiioe12

Alternatively, you could go with something smaller and lighter, like the FiiO E11. This unit is rated at only up to 300mW of output, so it won’t fully drive the beefiest headphones around, but it’s great for mid-range audiophile gear and is only $65.

If you want something more exotic, and more compact, check out the V-Moda Vamp Verza. Unlike other amps, which stand alone, the Vamp is designed to strap onto an iPhone, iPod, Android smartphone or similar device, which results in a more compact form-factor. The device can output up to 150mW of juice and lasts up to 7 hours. The downside, though, is the price; it’s a whopping $600.

Conclusion

Understanding amps is a bit difficult, but in all likelihood it’s not a quest you need to embark on. If your headphones are already almost too loud to tolerate at maximum volume, you don’t have an amp problem. You only need to worry about purchasing one if you have a high-impedance, audiophile set.

Do you use an amp? If so, what headphones do you use it with? Let us know in the comments.

Image Credit: Adamantios via Wikimedia, Daniel Christensen via Wikimedia.

  1. Chris Proctor
    July 18, 2016 at 11:19 pm

    I have a few pairs of headphones which I have always plugged in to the main amps up until the little box arived.
    My intention was just to use it around the house to help my phone give a reasonable output to my cans, this isn't by any means an expensive head amp just £60 so I didn't expect much.
    The sound is incredible for the money it runs my hd 600 and my akg 702 with ease it's the fiio Q1 amp/dac it can be used with a phone or desk top.

  2. MJ Ronnie
    May 26, 2016 at 8:17 pm

    I use Sony MDR XB30EX headphones paired with a sony walkman mp3 player (NWZ-E383) and i dont find a reason to buy an amplifier.

  3. kyy
    January 3, 2016 at 10:18 am

    hey, I recently bought the sony xb950bt, and should i get an amp? I mostly plug it into my iPhone although it's a bluetooth headphone but sometimes i also prefer to use it wired

  4. PaulWilson
    November 30, 2015 at 1:04 am

    The amp/dac world is dripping in snake oil. I own some Sennheiser HD650's. These have a very high impedance- 300 ohm- and therefore if any headphone needs an amp it's them. Indeed if you spend any time on headfi you will be told how amazingly well they "scale". Computer soundboard vs $100 combined USB+DAC? Apart from less background noise (which was barely noticeable anyway), absolutely no difference- and even there I'm not 100% sure the difference wasn't just in my head.

    Even though I can't even get a significant difference away from a laptop soundboard, they'll tell you with dead sincerity that the only thing that brings them to their full potential is some $10,000 tube amp

  5. Gaurav
    May 17, 2015 at 5:42 am

    Hey! I have the Yamaha EPH-100SL in-ear headphones. Should I get a portable amp, like the FiiO E6 / E11? Will there be any difference in the sound? I use it with my iPhone 6 plus.

    • Josh
      February 22, 2016 at 11:19 pm

      in-ear sets will always have a much lower impedance than over-ear or on-ear sets and except for a very very few and rare exceptions that include things like shure's $1000 in ears, you'll never need an amp for them.

  6. Zack
    April 1, 2015 at 8:27 am

    I have a Sennheiser HD 600 and am using it with a Ifi nano iCAN.

  7. Alex
    March 22, 2015 at 10:49 am

    Hi. Just bought myself Beyedynamic MMX 300, which will be used 80% for gaming, 20% movies and a bit of music. I'm not an audiophile and have no experience with high end headphones so unfortunately i started educating myself a bit too late on different impendancies. As it happened, i ordered 32 ohm version and now i read everywhere about the 1/8 rule. I started wondering about my selection. I expect my sound card (which i'm yet to buy) will have impendance output between 10-30ohm so:
    What kind of "real life" difference in sound can i expect?

    How badly will i notice the distortions if i use normal volume levels?
    Should i buy a small amp like Fiio with small impendance output and wire it between my Sound card and head phones - or is this just a really stupid question?

    Thanks!

  8. TheFu
    January 29, 2015 at 3:06 pm

    By the way, from personal experience: Headphone Amplification with an iPhone is also not needed with AKG K701, AKG K 702 (including 65th Anniversary edition), and correspondingly AKG K7XX (Massdrop First Edition). They are 67 Ohms and are okay with me. I also have the AKG K501, they are 120 Ohms and i have to use them at maximum or near Maximum Volume on an iPhone 4S so they may need amplification for most people.

    Rant ahead: "Increased Soundstage", "Tighter Bass", "Better Definition" are all complete and utter bullshit, even a DAC / AMP-Combination for over 1000 Dollars will NOT give you that kind of better experience. It has been disproven time and time again, there are many reasons why this group thinking still exists, confirmation bias / buyer's remorse are two reasons, and maybe because the "color" your Amp gives your music is something you like. But from a technical standpoint, the ONLY two reasons to get an headphone Amp is: Your headphones are hard to drive (100+ Ohms), or you want it LOUDER. That is IT.

  9. TheFu
    January 29, 2015 at 2:54 pm

    Douglas, the Grados work just fine with any Apple equipment, and every iOS equipment since 2005 has more than enough juice. For me personally everything under 100 Ohms works great, especially on the iPhone 4 / 4S (the are the loudest). But i do not listen really loudly. 32 Ohms you will be able to crank up to uncomfortable levels easily. Take care!

  10. TheFu
    January 29, 2015 at 2:51 pm

    Dan Smith, this argument is a myth in audiophile circles. If you can get your coil to swing violently enough to be loud enough, you also have the necessary energy to stop it precisely, with the exact same amount of energy. Do not spread that kind of unscientific misinformation.

  11. Douglas
    January 17, 2015 at 9:36 pm

    Hi, Will I need an amp for my pair of Grado SR80e (32 Ohms) to be used with Macbook Pro with retina display or with my iPhone 6?

  12. Dan Smith
    June 3, 2014 at 6:38 pm

    "If your headphones are already almost too loud to tolerate at maximum volume, you don’t have an amp problem. "

    This statement misunderstands the issue. The issue is not if the average volume is high enough. The issue is if the headphones can get enough juice to hit the brief high amplitude signals correctly. If not, you have distortion, even if most of the time it seems too loud for you.

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