I've been quite successful using lower volume settings on my CZ's... The information Dan-Pa. posted above made me wonder, so, out to my test bed I went... After ground balancing my CZ7 (volume at default of 4 which is the setting I use) checked the 8" silver dime and received a faint High tone (along with the occasional grunt of iron)... Moved the volume to 6, then 8, and didn't notice much difference... Moved the volume to 10, and WOW... That 8" dime was really sounding off... After backing off the volume on my headphones a bit, checked other shallower targets in the bed and was simply amazed... The shallower targets were much louder, as they should be, than the sweet unmistakable, and far more noticeable, sound over that 8" silver dime... From now on, I'm cranking the volume to 10 on the tector and backing off the volume of the headphones... I'm even going to mark the headphones setting, from the test bed, so I'll have the same sounding, or close to, machine wherever I go...
-Robert