Mastering should mean spectral balance and dynamics. In an era of loudness, air and punch have become a rare commodity.
Streaming platforms like YouTube and Spotify normalize louder tracks to around -14 LUFS. While a -6 LUFS track might seem powerful next to a -14, it actually sacrifices all micro-dynamics, resulting in a much weaker overall sound. And not to mention, there is no proven link between loudness and success.
hint: Right-click on any YouTube video and check "Stats for nerds" to see the attenuation amount.
The key to good sound is spectral balance – if it's right, a track sounds good on every setup. As mastering typically raises the level, the key to an objective comparison is the exact same loudness. Often before and after comparisons are not volume matched, making "louder" seem automatically more bright and powerful. Here you can compare some original masters and mixes at the same loudness:
A/B comparison →