I just got around to reading this thread all the way through .....It aprears to me, and I could be wrong, that this mod not being explained, and there is really no REAL evidence that it does anything , it seems fishy to me ......Then reading more about the "tone" changes that people do to hear targets better, I can't help but think about another company that offers a "low tone" and a "High Tone" machine ......The "High" tone machines are claimed to have a better target tone seperation , and the actual character of the tone is better meaning you can better figure what target you are hitting by a "scatchy" tone , or a certain "chirp" that you can better hear when running a high tone machine .....Perhaps this is more a case of being able to better hear your targets , hense the feeling of better depth ..... Most people that have hearing problems , can't seem to hear low tones as well as when their hearing was good ....High tones are heard much better ...... This would make more sense in our world of detecting too !!.... I'm getting my first GT soon ....I will give it a quick listen, but if I can change the tones to higher tones, I am going to change them and start fresh running a "HIGH TONE" machine ......As wildhere was mentioning that he adjusted the tone using a music program that best suited his hearing ..... I would hope that this mod is more than an audio adjustment , but with the dancing around the issue, and no real solid answers , perhaps this is the deal ... Whether or not this is the case , perhaps changing the audio yourself to what best suits your ears , might help your finds ....Agian, I am only speculating after reading this thread thru .....Thanks..Jim