Mastering is the last step between a fully mixed song and publication or premastering before the actual mastering of a pressing plant in a CD production.

Since there are many myths and untruths in this area, it makes sense to involve a professional mastering engineer in the project who knows exactly what he is doing.

Here are a few points why this will definitely be worth it:

A subtle but very important point is that the production is completed by someone who has enough distance from the project. If you have already produced and/or mixed the song, it is simply not possible to judge it through this lens. You are also far too emotionally involved in the project. The experience you have when listening to a song for the first time is crucial to evaluating significant points. One of the tasks of a mastering engineer is to consult with those involved if something was overlooked or, more accurately, unheard during production or mixdown.

An optimal mastering should implement the mixdown and the feeling that the song conveys in the best possible way. Mastering means 1-2dB here and 1-2dB there. Small but targeted adjustments are made to create the best possible end product from the song and correct problematic areas of the mixdown. This ensures that consumers get exactly what the artists, producers and engineers had in mind, no matter what medium or aggregator the song is played on.
 
Every song and every album has different problem areas or points that can be improved. From low-end correction to annoying resonances, adjusting the frequency spectrum or adjusting the stereo field, phase problems to songs that can still tolerate a little coloration/analog warmth. A mastering engineer knows exactly what is needed to achieve the best possible product.

The mastering process is also about making a song or album as homogeneous and coherent as possible in order to implement the performance in the best possible way, to create a pleasant and appropriate listening experience and to optimally transport the vibe to the listener.
 
As a mastering engineer, you know the tricks such as how the highest possible loudness can be achieved, of course adapted to the respective genre as well as the song or album at hand, and still maintaining the desired dynamics. The transients remain crisp and the song sounds balanced and pleasant. Powerful bass, silky mids and crystal clear highs, this is the work of a mastering engineer.

Nevertheless, the loudness of a song or the song of an album should be an artistic decision of the mastering engineer and can be very individual. Even if this of course depends on a different genre, this decision should benefit the production. A good mastering engineer is not just guided by numbers and standards.
 
The know-how and equipment are crucial to give the productions the finishing touches, to make the best possible use and to deliver them with the highest industry standards.
 
All in all, the experience and the decision to specialize in mastering make the big difference. As a mastering engineer, you know the standards, know how they can be optimally implemented and have a wide range of comparisons.