See the first stage is the recording, then the production , then is the mixing stage and the last one is mastering. In this phase the song get polished and refined holistically, i mean it gets an integrated perspective.
I will not say it is window dressing but it is more of a final touch up stage, and the most important thing is the person who is going to do the mastering , i mean he better be more experienced then you or the mixing engineer because it is skill game that all , the mixing and mastering perceptive are very different, they are not same atall, i mean you can be a real good mixing engineer and at the same time you can be really good at mastering but it is always advisable to have a good mastering engineer who is just into mastering because mixing and mastering are totally different process .
Mastering plays a very crucial role in listing experience and it is multi dimensional in nature.
Mastering brings the level of your mix up to match with the rest of the tracks in your library or streaming platform. And that is really important because if you want to make your song punchy and energetic cross platform this is the only way that you master the track real well and optimize it for all platforms.
Making the track sound , well balanced and punchy without clipping the listener’s playback system is the game, and yes this game is all about mastering.
See apart from audiophiles, rich people and engineers, most of the people are just listening the tracks on 100 dollar or less headphones and speakers and that is a harsh reality.
Another key job in mastering is to optimize the tonal and frequency balance of your track so it sounds real well across multiple devices, be it the low end speaker , mid range speakers or high end PA systems.
The online streaming platforms have strict standards for audio rendering and they will normalize your track to a certain level, i mean all of them have a certain INTEGRATED LUF rating which they use to normalize all the tracks, a good mastered song will deal with all these issues because it will be stream ready, yes it doesn’t matter how good your song sound good on your PA it better be stream ready and that is only done by adjusting the LUFs rating during the mastering stage.
Mastering is more of a problem solving kinda situation where you are trying to solve the problem you have, see when recording lot of songs it can have weird room noises, it can have phase issues , it can have bad gain staging, or it may have lot of masking frequencies which are just masking the bass, kick etc etc , so in the mastering phase these things will be rectified in a good way, i mean that is what is to be done during the mastering stage ie to get the clarity and the punch of the song, which is only possible when the tonal balance and the clarity of the song is not compromised.
Mastering is a mix of technical and creative process, it is a very important and integral part of the song life cycle. I mean the mastering style may differ for a rock song, a pop song , i will rather say it is more genre specific and hence is a domain which is evolving over time and with new cool powerful and highly capable plugins are just making the whole domain evolve at the faster pace.
Mastering is super important and please dont release any song without mastering, you can use lot of online services to master, but do it, without mastering i am pretty sure your song will not be LISTENER READY or lets say STREAM READY.
So in the end, these are really important stuff you have to take into consideration, SO MASTER THE SONG AND THEN ONLY RELEASE IT, WITHOUT MASTERING IT IS JUST WASTE OF TIME AND RESOURCES.