IM-16 is actually zero discriminate for all refined metals. We have the same as IM-16 if we simply clear the screen in Smartfind. One way to think of Audio1, 2, and 3 is a frame of data. Audio1 takes a longer look at each target so give a longer sound that trails off. The problem with Audio1 is the long sound can cover up a deep faint sound of co-located targets. I just about always use Audio1 but it can be a blessing and a curse unless used properly. I like to use the small coil and audio1 but am careful about sweeping the coil slowly and when there is a hit then pinpoint and make sure I am not masking a target with the longer sound.
I think most users seem to agree that learning the sounds is most important so I see nothing wrong with going to Audio1 first. It has a lot to do with prior experience, IMHO, and the type of detector if any operated by the user before the Explorer. I don't think a DFX user would have much difficult making the switch but a user that has mostly used a more basic discriminator with 3 tones would find it a little more difficult to switch.
My preferences would be to experiment as I felt the interest and then ask for answers on the forums. I am not sure there is any specific best way to learn the machine.
