I just got an AT pro and Im pretty happy with it so far even though I havent been able to get out and use it for the cold , snow/ice here. The only issue is there is sort of a high pitched tone coming from the headphones that almost sounds like what you might hear from old sound equipment if the amp was turned up too high. Starts as soon as the detector is turned on and dont stop until turned off. I only have the stock headphones , no other ones to try in an effort to see if the phones are defective. Without the headphones the sound isnt there , sounds normal. Even with the headphones the detector seems to function fine it just has that annoying sound. The phones are fully inserted into the jack and locking nut tightened , installed correctly. Has anyone else had this problem ? Im gonna contact Garett about it Im just wondering if this is a common thing or if anybody had experience with it and maybe know some simple way to fix it ?