Rarely do crank it up all the way, too, as I have seen just as much treasure come from less than 8" where I hunt,
and I still find dinky pieces of metal with it on half the sensitivity, and the threshold just past a whisper
(of course, depending how noisy outside my headphones are at the time...!).
My machine isn't modified, so in mineralized soil, without my DD coil, turning up the sensitivity just messes things up