humming noise

Hello frends, my audio gear is as follows:
Well Tempered Labs Classic TT
JLTI Diamond phono stage(Alen Wright design)
Shelter MM cartridge
Krell Amp
Usher speakers
I have been enjoying audio bliss, for approx 30 hrs since buying, the shelter, "black silence"
I forgot, to check the "overhang", of the cartridge, so adustered it, it was only out by a small amount, to make it spot on, I had to move the cartridge, a small amount, towards the end of the arm tube, to the spot on area, however when I turned the amp on a loud humming noise, is now coming, from both speakers, I checked the cartridge clips, and all seems O.K., I can't believe that buy moving, the cartridge, a very small amount, would cause this!!,
Hoping someone can help, as I live on the far south coast, of Aust, the nearest audio shop, is 3 hours drive, I'm not sure they be able to help, as turntables, are rare here!!
Many regards
David