Of course with true analog equipment, there isn't really any granularity along the range of controller, but that's kind of the point I'm getting at. If you were dialing in a real amp, you wouldn't be able tell where the knob was with that much precision. Most analog knobs if they're labeled at all are labeled in increments of 10. You may be able turn the knobs in half increments of that with some precision, but even then, it becomes tricky.

As far as what difference in sound pressure levels a person notices, 1 dB is generally the difference that will be just noticeable. Of course that doesn't really relate to the way the dB scale on an EQ works. How one perceives the difference on a recording depends a lot on how the recording is played back.

Regardless of all that, I still don't believe that there would be noticeable difference in the tone stacks if you had the ability to adjust them in increments that would essentially be 1/1000th of the total travel of the knob.

I even take it a step further. If possible, it's best to have someone not in the band do the mixing. But that's a luxury that's getting harder and harder for many bands.