I went to a party once where somebody had rented a massive PA and by the time the second (of eight) bands took the stage, the soundman (I.e.: the guy who rented the PA) was passed out.
The garbage coming from the PA was horrific, and somebody had to do something quick. I had no idea what any of those knobs and sliders did, but I stepped up anyway, if only to shut down the ear splitting feedback. Nobody else did.
Meanwhile, the band kept playing, and the singer made a big show of his disappointment in my lack of ... well, anything ... And people all around the board were yelling at me; turn up the singer! More bass! More drums! Etc. it was absolute pandemonium, and they kept it up all night. Instead of being hailed as a hero, I was cursed and reviled among men.
I resolved to learn just enough about mixing boards so it never happened again. (Resolved means; when I get around to it in my world. Just ask the Foghorn.) I bought the Yamaha Sound Reinforcement Handbook and got all the way to page 4. Woo hoo!
A couple of years later I was in a killer band and we played a festival, and the sound was superb. We were on early, so after our set I hung out at the board and just watched. Between bands, I complimented the soundman and we got into a discussion that is still, to this day, the single most productive conversation about sound that I've ever had.
He showed me the layout of the board and how it pertained to gain structure (remarkable that neither topic would have sunk in to my rather thick, yet handsome skull without the other, but because he equated gain with each knob, I GOT IT!)
The most important thing he told me was to get a set of Sony 5706 flat-response headphones and use them to familiarize each knob and slider so I'd get the FEEL of what it did, purely by ear.
He said that the trim/input/mic knob was to set the hotness or sensitivity of each mic or instrument, and that you wanted as much out of it as you could get without distortion. Easy! I could listen for it in the headphones, and it would be just like the singer was singing directly into my ear. Once it's set, don't touch it.
My god, that simplified things. He also said to never let a singer go check check one two three etc., because it was worse than useless. Have him sing a song, because with headphones you'd have the trim set in about five notes, and could move on to the next channel. It was all about finesse.
Things like; you should know what the trim pot setting is for an SM-57 or 58 without hearing a note, roughly and he was dead right. (And I do )
He told me about using a parametric EQ to eliminate the bad, rather than staring into space, going; does this sound better than THIS? Crank the level, sweep for what sounds worst, turn the level down and away it goes. (It's startling through good headphones, believe me.)
It was all about getting the basics, as quickly as possible. Boy, did I Hoover every word of the Sound Reinforcement handbook after that. It was such a pleasure, rather than the drudgery of my first attempt.
I'm not telling you this for my ego's sake. Quite the contrary. I was astounded by my ignorance, and how much I could learn from listening with headphones.
My favorite tip was; nobody bothers you when you have headphones on. He was absolutely right.
I apologize for the length of this rant, but it was important to this topic because I learned how precious my bass sound ISN'T, in the great scheme of things.
Somebody posted a video of their band a while back, and even though he was a MONSTER bassist, I cringed because they only faced the audience for a few seconds and spent the rest of their time twiddling with knobs on their amp and bass. I don't think they realized that everyone else in their band was relaxed and smiling, and they looked like deer in the headlights. Just petrified.
I was just like that for a long time, until somebody way smarter than me (which admittedly ain't saying much) told me to get some headphones and find out what those knobs actually sound like, and how much of your sound is actually in your hands. (Especially because upright bass is my primary instrument, which includes all the weird harmonic stuff that happens when you smack the crap outta the strings about two feet from a couple of Fishman transducers clipped to the top of the [wooden] bridge. At serious volume levels you can potentially make people ears bleed.)
It literally changed everything about the way I play bass, and focusing on the FUNCTION of bass within an ensemble. I try to sound as close to the bass drum(s) as possible. Like one of my favorite drummers said; you play like you're hiding from the police.
Yeah, that's why I get the gigs, though.