[size=large]As you know the sensitivity is basically the size of the "receive antenna " of the returning signal. As the sensitivity increases, EMI will now start to being received by that "antenna". That is controlled by turning back the sens. or moving to another area to hunt. The Gain , according to my understanding, is that it doesn't enhance the returning signal but amplifies the audio of the target after that audio has been produced by the detector's circuitry. There may be a potentially audible target buried in the audio output and by enhancing with the gain, you can now hear it. There will be times when you can run the detector wide-open in both Gain and Sensitivity but in some areas that may not be practical because of EMI, mineralization or overloading. The Gain will enhance the target regardless of where Sensitivity is set.. but that doesn't necessarily mean you can always crank the Gain wide open either because it will start boosting the EMI hidden in the audio.
My mind don't work right anymore, hopefully you can appreciate what I am saying.
Too, Rosi if you want to add and / or correct me, I welcome that, too. Ya never get too old to learn... Richard Backwoods[/size]