system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If listening to music at high volumes is bad for your ears, why are headphone / PC amplifiers such a big deal?

It doesn't make sense to me because both my PC and my phone... and basically all of my devices... are insanely loud on their own. I see amps that go in-line for sale all over the place online though. Does it improve quality or something?
gpt
Headphone amplifiers are not merely just for increasing the volume. There are different specification for each headphones namely impedance (ohms) this value means it is harder to drive (or just harder to power). 

If you put a 600 ohm headphone on a soundcard/headphone amplifier that could only power a 300 ohm headphone, the volume that will come out of the headphone can be adequate but the volume knob will be up almost tonits maximum. Thus somewhat distorting the sound to increase volume.

 The sweet spot for volume to get the full quality of recording is at 50%.