I'm gonna keep this simple.
The quieter the sound, the more bass and treble there needs to be for the tone to "sound" even to us. At low volume , its harder for us to hear bass.
As the volume goes up, our ears start to hear frequencies more evenly.
This is why the bedroom tone doesn't work at gig levels.
We need to boost the lows at low volume to hear an even tone, but at high volume, we need to remove that boost to hear THE SAME TONE.
I know that may not make sense. But it's how our ears work.
This chart represents how much power from each frequency range we need to hear to hear even sound at specific volume levels.
Notice at low volume we need to hear a LOT more bass for it to sound even with the mid range.
Once we get to gig levels (around 120db)
Our ears are hearing frequency energy much more evenly. At high volume , our ears are almost as sensitive to bass as mids. In other words, we no longer need to boost the bass to make the sound full. In fact, depending on your amp and cab, you make actually need to cut bass just to get an even , not super bass heavy sound.
This is super important to understand. Once you fully grasp the concept, you will realize how much bass and treble you need to get your tone is volume dependent.
That the louder you are, the less bass you actually need to sound full.
When I set up for a gig, I like to cut the bass completely and get the mids up to volume, then add the bass back In a little at a time until the sound is full. For me, that usually means my bass knob is left of noon. What works for you will depend on your amp and cab, the sound you are going for and the room you are in. Those are different discussions though.