From the website FAQ: Mastering is really two parts. First, it's the final creative step in the process of recording. It's also the first step in replication, duplication, or distribution. It's where we make every effort to make your music sound it's best on whatever format it's being distributed on and taking the limitations of those formats into account. It's so that your music sounds good on Spotify, a cassette, a CD, a vinyl LP, etc. But what that practically means is a c