Clearly, it is important that an artist see properly, what they are doing. If she can’t see properly, she might make a bad decision on how she mixes her colors and how she applies them. She might in fact feel that she is creating a certain mood or expression, not realizing that the mood is set by the lighting in her studio and that it actually appears completely different when lit differently. Worst case scenario, the intended emotion actually breaks apart completely under proper lighting. In effect, the lighting is a tool the artist uses to ensure a standard of quality in her work.
The same can be said for the gain staging of our signal chain both in and outside the box. The right levels enable our gear to work flawlessly (this goes for plugins too!), without introducing any unintentional artifacts which might elude our control. As I am sure you have experienced, we tend to lose ourselves in the music very quickly, making any objective assessment very difficult. If we don’t take care of our gain staging, and let levels run wild, we might (and most likely will) introduce artifacts that negatively impact the punch, depth, and clarity of our music.
As it turns out, gear designers have long ago agreed on a standard level, at which their gear functions optimally, and unintentional artifacts are minimized. To make things easy, they called it 0VU. When digital came along, that level had to be translated into the digital domain, and, for various technical reasons, ended up being -20dBFS (the level in our DAWs). Important to note is that in practice this refers to our average levels, like the ones an RMS meter would measure. So ideally, we want our average levels to hover at around -20dBFS, allowing peaks to hit perhaps -9dBFS.
Going back to the painter analogy, you can think of this as comfortable full spectrum light, like you might get from a ceiling window on a beautiful day. It’s not to bright, and not to dark, with a good balance of all colors in the spectrum. Given bad lighting, the painter might choose a shade of red that actually clashes with another, without even noticing. Similarly, by running our levels to hot into a plugin, we might introduce artifacts that actually sound nasty, but we don’t notice, because we are so engaged in the creative process.
So in essence, proper gain staging is the tool that allows us to maintain the highest quality audio signal, in sight of the danger of loosing objectivity during the creative process, and unintentionally letting our gear negatively affect our work.
If you’d like to know more about gain staging, have a look at this article on SoundOnSound