i have been using a fishman pro plat pre/di with really great results until last night. it had really annoying hum when run into the pa head. at first i thought it was a bad cord. i checked all the cords and found when i touched the 1/4 cord at the input the hum went away. the humming noise was much louder with a xlr cord from the pre to the pa head than a 1/4 cord, but still was humming. i figuredit was a grounding problem, but the ground lift made no change to the hum. the only way it would go quiet was if i was contacting the cord with a part of my body. interesting enough when i toggled the pre/post eq switch the hum went away in the pre position but was right back in the post position. anyhow i did the gig with a 1/4 out to the pa head which was still humming but at much less volume than the xlr cord. the hum was not so loud with the 1/4 cord that i couldnt use the pre, but still it sucked. we have played this venue many times without this issue. the only variable was we were plugged into a different outlet than usual. after the gig i decided to plug the pa head into the outlet we usually use at this venue and had the same problem. i played 2 gigs the night before at 2 different venues with no issue. and today i plugged the preamp into my acoustic image contra and it was dead quiet. anyone have any idea what may have caused this annoying hum? i'm guessing it was the venues power supply, but like i said i've played there multiple times without this issue. the guitar player was using a lr baggs preamp and he had no hum noise at all from his. i have a gig tomorrow night and now i'm starting to worry i'm going to have this issue again. any ideas?