Amp

An amplifier is the muscle. It gives a sound signal the power to do actual work.

The signal that comes out of a DAC is just a blueprint. It’s a clean, detailed, but very weak electrical whisper. It has the right shape for the music, but it doesn’t have the strength to physically move the parts of a speaker and create sound waves. You can’t power a speaker with a whisper.

This is true for any audio source, including a Raspberry Pi with a DAC HAT. That setup gives you a line level signal, which is the standard, quiet signal meant to travel between audio components. If you connect a pair of regular, passive speakers directly to a DAC, you will hear almost nothing. They need a real push.

An amplifier provides that push. It takes the low power line level signal as an input and creates a powerful, high current copy to send to the speakers.

For a Raspberry Pi, this can be a separate, traditional amplifier box. Or, it can be another HAT that stacks right on top of the Pi. These amp HATs turn the whole setup into a complete, self contained audio player. The Pi is the brain, the DAC is the translator, and the amp is the brawn. It becomes a single small machine that just needs power and a pair of speakers to make a room full of sound.