Do I need a Headphone AMP?
When you consider that a good speaker needs to be paired with a good powered amplifier to sound its best, similarly a headphone, which functions as a miniature speaker would need a good miniature powered amp (i.e. a headphone amp) to bring out its best too.
You would be surprised at the level of audio performance you could get when a good set of headphones is paired with a good headphone amp and good audio source. While speaker systems out-perform headphones in terms of imaging and visceral impact, note that headphones can deliver more superior resolution and detail. The most common reaction folks have with their first experience listening to good headphones with a good amp is, “I’ve heard stuff I’ve never heard before, I’m going to have to listen to my whole music collection over again.”
In addition to the dramatic headphone listening improvements you’ll get with a quality amp, you’ll also find a good headphone amp will ably serve as a pre-amp, which allows switching between multiple player inputs and the capability of driving both headphones and providing a pre-amp output for your speaker system.
Most people probably have good quality music stored on their iPods and use full-sized headphones. But relying on the power-limited amp in the iPod won’t transmit your headphone’s full potential. Adding an amp between the iPod and your headphones can and will provide a significant improvement.
Having said that, note that the size of your headphone will give you some clue as to whether an amp may be warranted. Most earbud and in ear headphones are typically very efficient and are less likely to benefit strongly from an amp. Many larger headphones will benefit, or even require, a headphone amp to reach listenable volume levels with portable players. If you are listening to your music on a computer a headphone amp with an internal digital to analog converters (DAC) will dramatically improve your listening.
With a portable player, use a “line output” when available to drive a headphone amp. If no line out is available, use the headphone jack to send the signal to the headphone amp.