I have a 3 year old or maybe 4 year old explorer II, the volume has always been to loud even with the threshold on one, does this unit adjust volume with the head phone settings, the original Koss head phone did not have any adjustment knobs. Last week I used this unit in a hunted out park and it behaved like a normal detector with the volume issue. Found SL quarter and two other silver coins and 3 silver rings, but now unit is loud again. Unit was bought new,thanks for any help