The Amplifier - The Muscle

An amplifier does exactly what the name implies: it takes a tiny, weak electrical signal from your computer or phone and amplifies it until it has enough brute force to physically move the speakers in your headphones.

If high-ohm headphones are a heavy oak vault door, the amplifier is the muscle required to move them. You can plug the 300-Ohm HD 650s directly into a laptop, but it’s like putting a moped engine inside a sports car.

It will roll down the street, but you aren't actually experiencing what the car was built to do.
A great amplifier grabs the headphone driver with absolute authority, ensuring that when the music says "stop," the driver stops instantly, and when it says "explode," it explodes with full force.