theres a Noise that is normal, its the nature of the mixer components,
another is the noise generated by the turntable,
another is generated by the wires and thats what you probably can eliminate ..
its too much noise, ?
wheres that sound come from?/ Urei only or the TT ??
Is your electric instalation grounded? do you have neons? or lighgts or dimmers in the same electric line?/