What are headphone amplifiers and what do they do?
The world of amplifiers can be confusing for non-audiophiles, but hopefully this headphone amp buying guide will help answer your questions.
An amp essentially takes the music source, whether that be your iPod or home computer, and amplifies the signal it sends out to your headphones.
What most people aren’t aware of is that, if you own a device that plays music, then you already have an amplifier right now (albeit not the best quality one). Every device that plays music uses an amplification circuit of some kind to power your headphones. So, if you own a PC, laptop, tablet, smartphone or mp3 player, then you already have an amp!
The problem is that the the amplifiers in these devices usually aren’t able to power high end headphones. Because amplifiers use more power, battery powered devices tend to use amps that are as low power as possible.
Headphone amps work, according to Wikipedia, by allowing for higher possible volumes and superior current capacity than the smaller, cheaper amplifiers that you’ll find in most music players.
Do I Need a Headphone Amp?
Every set of headphones (except for Noise-Cancelling Headphones, which I’ll get to later) will benefit at least a little from amplification, although the degree of benefit will vary widely. Here’s 3 things to consider when deciding if your headphones need amplification:
- The Type of Headphones You Have (i.e. Over-ear, On-Ear, IEM’s) – Generally the larger the size of your headphones, the more amplification will help to improve the sound of your headphones. You can imagine that tiny earphones that fit in your ears don’t require a lot of extra juice to drive them.
- Price Range – A general rule of thumb I like to use is that if you spend over $100 on headphones, you should consider an amplifier for them. Obviously a full-size set of cans like Audio-Technica’s ATH-M30 would still benefit from an amp, but when you get above $100 the headphones tend to be designed with the intention that they will be driven with amplifiers when they’re used.
- Output Impedance –
When you’re browsing for headphones, the specs will list the nominal impedance, measured in ohms. As a rule of thumb, the larger the ohms, the more power is required to ‘drive’ those headphones. So a sub-$100 set of headphones like Audio-Technica’s ATH-M30’s have an impedance of 65 ohms, whereas the notoriously power-hungry Sennheiser HD800’s have an impedance of 300 ohms.
What’s the Benefit of Amping Your Headphones?
The higher end headphones are better able to deliver more detailed, spatial sound that will change how you listen to music. If you plug in $300 headphones into an iPhone or iPod directly, you’ll probably find that the volume is low and sounds flat. When you drive them with an amp, the most common thing people report is that they hear details in the music that they’ve never heard before.
When You Do Not Need A Headphone Amplifier:
A headphone amp isn’t always necessary, and in these cases, there is no reason at all:
- Noise-Cancellation Headphones – Noise cancelling headphones already have an amplifier built into the headphones themselves.
Types of Headphone Amps
- Portable Amps – powered either by batteries or a USB connection.
- Desktop Amps – Larger amps designed to be used with your PC, music server or laptop.
- Full Size Amps – As big as other home audio equipment, like a receiver,. Uuslaly the full size amps can give you the best quality sound performance. Designed for permanent listening environments.
Headphone Amplifier Specifications
These are the specs you will use to compare different headphone amps before deciding on the right headphone amp for you.
Total Harmonic Distortion (THD)
– 1% or less is better.
Signal to Noise Ratio
– This is a measurement of the headphone amp’s noise (bad) vs. the source music signal (good). A larger ratio is better.
– The impedance range of headphones that the amp is meant to work with. Higher is generally better.
Headphones are eco-friendly when compared with home speakers. Most headphones need less than 200mW to reach maximum output. An amp that can drive 500mW will be able to drive most headphones.
Best Headphones Amps Under $100
Here is a list of 3 Budget Headphone Amps that I recommend for your headphones. These are all portable headphones, and so are meant to be used with your laptop, tablet or smartphone.
One caveat is that you’ll eventually want to buy the AC adapter. As is, it runs on four AAA batteries that will last about 15 hours. The AC adapter unit is only another $15, but after a few battery replacements the value of the Adapter definitely came into full view.