MASTERING YOUR MUSICA song is typically mastered at the final stage in the recording process and is concerned with adjusting equalisation and dynamic enhancement in order to improve the sound translation on all playback systems.
Don't confuse mastering with mixing!
Mastering, is the process of taking that final mix and giving it a final professional polish.
The mixing process involves taking each individual audio part within your song and working with their volume levels, EQs and effects etc., to create the final "mix".
Remember that the mastering process can not change the elements within a song, such as deleting a guitar part or turning down the lead vocals, because we will only have the finished stereo file to work with.
If you need changes to be made to elements within the song you would need to go back to your "mix" and alter it there before mastering.
Master / Stereo Bus
For the best possible starting point, it's advised to eliminate any eq, compression, limiting or other effects from your DAW (e.g. Pro Tools, Logic, Ableton Live or similar Digital Audio Workstation) or your mixer stereo master bus.
To avoid clipping of the stereo master bus before mastering, make sure you leave at least from -3 to -6 dB of clean headroom for your pre-master stereo audio track.
If your audio signal is redlining or peaking (e.g. at 0 dB in your DAW or on your mixer) it essentially means that you have no headroom left and output adjustment is required.
Decrease the output to a healthier -1 to -3dB range to allow maximum flexibility when mastering your tracks.