I just went through the same thing. While any of the above answers may fix your proplem there is one more place to look. The cables from your turntable to your phono stage are very sensitive to RFI. I kept changing cables until I found that in my system a heavily sheilded coax cable did the trick. Now there is nothing but blackness between the musical notes.
Eliminating humming & buzzing
What is the best way to have a clean sound? When I hook
up the grounding connector from my turntable, it reduces
about 95% of the humming/buzzing; but not all of it. The
noise is still there even if I unplug the power from the
table.
Is this simply a grounding problem, or is there something
more that I need to do? The table is hooked up to a
receiver which is not at all grounded; I just connect the
table ground to the ground in my power strip. Kind of
primitive, I realize, which is why I'm asking here.
Thanks!
Mark