my signature is flat to the last band on the eleven band analog bass EQ with a Q of .72, unless I am listening to Steely Dan: Two Against Nature, then i tweak it back a whisker....Teachable moment: flat is relative because human beings don't measure they hear. Metering is a scientific process of measuring the physical movement of air. Hearing seems on the surface to work that way but in reality is a whole lot more complicated. What sounds flat or balanced at one volume level will sound completely different at another volume level, even though it may measure flat both times. This is why the loudness control used to be so common. See Fletcher Munson curves.
Now this creates a bit of a challenge for recording engineers. Because they want to get a certain sound. But they know the sound they get changes dramatically depending on the volume its played at. They tend to monitor at a fairly high level, and tend to EQ for that level. They know a lot of people will listen at lower volume, or higher, where either way the EQ will be off. Most people though when they are really listening will tend to have the volume fairly high. So they EQ for that level.
So you can twiddle all you want with your EQ, it will only ever sound right at the one volume level. Even then, only with recordings that were mastered at about that same level.