Stem Mastering enables the mastering engineer to have more control over the outcome of the mastering session. Instead of dealing with a single stereo mix of the music the client supplies the track as several discreet stereo sub-mixes (stems) of the main instrument groups like: vocals, guitars, keyboards, drums, bass e.g.

By processing each group separately the resulting master can have much more focus and detail than an ordinary mastering process can achieve. This is the best option for artists, engineers, and producers to get the absolute best sounding final master from their music.