Louis Lazaris of CSS-Tricks listed AmplitudeJS as one of his favorite finds of 2017: https://css-tricks.com/front-end-tools-favorite-finds-2017/
He embeds a CodePen that pulls MP3s from our servers. It generates so much traffic that our monitoring sends us alerts in the sudden spike in bandwidth. Since our Google Analytics isn't being loaded (because the MP3s are being directly streamed), our first assumption is that we are under a DDoS attack.
After some Googling, we find the article and now finally understand that all of the traffic is legitimate 😅