Somewhere along the way “louder” started meaning “better,” and master faders everywhere have been pinned against the ceiling since. Here’s the thing the meter is trying to tell you: that last stretch isn’t volume. It’s damage.
What headroom actually is: the space between your average level and the point where the system starts lying. Digital clipping isn’t warm. PA limiters saving you all night isn’t dynamics. A master bus living at -6 dB means transients — the crack of a snare, the front of a vocal consonant — still arrive shaped like themselves.
The live version: if the only way the mix feels big is the master at zero, the mix isn’t big — it’s crowded. Balance, high-passing, and taming the two channels fighting for the midrange will buy more perceived loudness than the last 3 dB of fader ever will.
The studio version: mix into headroom and let mastering do its one job. Slamming a limiter on the 2-bus to impress a client on Tuesday makes a mastering engineer un-slam it on Thursday, minus the transients you already spent.
Loud is a decision you make once, at the end. Headroom is a decision you keep making the whole way there.