This is the standard practice for mastering a song. The artist sends a stereo file of their final mix which the engineer puts through the mastering process to adjust and enhance the song to achieve the highest quality sound and optimal loudness.

The artist sends files that have been summed with processing into six stems grouped from the mixed tracks: Kick, Drums, Bass, Synths, Effects and Vocals. This gives the engineer the ability to make small changes and enhancements to the balance and sound of main elements in the mix while maintaining the original vision from the artist.

The artist exports all individual tracks from their session with all processing (reverbs, delays, compression, panning, etc.) which the engineer sums to the best possible groups to treat in the same way as a stem mastering. This gives the engineer more flexibility than a standard stem master and allows them to make changes to individual instruments or vocals in the mix to fix any issues without fully mixing and changing the balance.

This gives the engineer full control over all elements in the track. The artist sends all tracks without processing and effects and the engineer starts from scratch in order to obtain the best possible balance and sound. A full mix includes everything from leveling and adding excitement to drums, making synths and basses come alive, controlling vocals and adding effects, final mastering, and anything else that is needed to achieve the proper depth and most expensive final product that is expected in the industry.