Amplifier myths
After you look at earphones for your mobile phone, and decide to get something better, people suddenly start talking about DACs. Meaning, headphone amplifiers. As usual, there is some truth in most of the things people say, but not all,
You need a DAC
Usually false. A DAC is a Digital Audio Converter. To plug headphones into a mobile phone, you need a DAC followed by an amplifier. Not many people need a DAC alone
You need a headphone amplifier
Your phone already has a headphone amplifier. See About Headphone Amplifiers
Headphone amplifiers work on Apple or other phones universally
Manufacturers and advertisers would like you to think so. But usually amplifiers are made for Apple phones or not. On the wrong phone, they can work badly, or not at all
Cheap headphone amplifiers can make the sound worse!
True. If you have an expensive phone, they may not be as good as what is in the phone
An expensive amplifier improve the sound on anything
From reading reviews, you might think so. But, however expensive the amplifier, connections can fail. And an amplifier will not change everything—replay still depends on the sources and headphones
No point in buying a separate amplifier for cheap gear
False. I’ve not heard or seen this written anywhere, but it seems to be an implication hanging round many reviews. In practice, a separate amplifier can make a huge difference to a cheap setup
Spend more, get better build
No. Headphone amplifiers are an active market so you will get value for money. But some manufacturers may spend the money on power supplies, electronics. or features such as optical inputs, volume controls, or input indicators
Spend more, better sound
Generally, you’ll get better power supplies and electronics. But will it work for you?
Specifications
Retailers love printing specifications. Only a few matter—is the amplifier made for Apple phones or not? Can the amplifier operate the switches on your headphones? After that, I’m struggling. If you listen to high‐quality music, can the inputs handle higher sample rates? In some (rare) cases, can the amplifier drive high‐impedance headphones? Can the amplifier drive by balanced inputs? That’s all you need to know
References
Long article, plain coverage about headphone amplifiers. You can tell I disagree with much of what is said there, but it’s an alternative point of view,