Technics 1200 Ortofon and Mcintosh

Recently purchased one of the last Japanese made Technics 1200G. 
Paired it with Ortofon Cadenza blue and Mcintosh C2600 Phono preamp. 
Rest of equipment: SF Elipsa Se, Mcintosh MC

I am hearing a loud buzzing noise coming from both speakers when I connect TT to phono. 

This happens even when the music is off. I hear it at 40% volume up. The needle on my MC452 shows 20-30 watts at 50% volume on Preamp. Keep in mind, music is off. When I listen to music it is less perceptible but I sure its still there. 

I grounded TT to C2600 as directed. I'm using a separate sounding wire. 

I tried changing cables, using Shunyata, Nordost blue haven, and cheapest Audioquest cables. The noise was highest with shunyata, less with nordost and surprisingly less with cheap AQ. Regardless, the noise still very severe and distrurbing at 50% volume when the music is not playing. 

Is this  a normal phenomenon? Where could the problem be?  I replicated these findings with my second amp, mastersound 845. Otherwise my set up runs perfectly silent with digital sources. 
Play around with your head shell connection to the tone arm. Does the buzz change if you press on the locked head shell?
Finding the noise when playing analog can be difficult at bet but try dressing the cables better and separating the equipment away from another better a lot of times it is the simple fix that works the best.
This is a very loud buzzing noise, given high end equipment involved  I suspect there should be a clear culprit 
Check the ground, could be a bad connection within the TT.  Just sorted a similar problem on a vintage Dual CS-5000.
Could sound surprising, but I found that sometimes disconnecting direct ground wire between my Technics 1200GR and phono-amp reduces noise. Anyway phono-cables provide such connection between grounds, so additional wire could create a loop. So my suggestion is that you try to remove your direct ground wire between TT and preamp. 
An earth loop certainly.

But if the buzz is equal on both channels, this exonerates cartridge connections and indeed all connections affecting a single channel.

The buzz is 'loud'.  So the fault is something gross.

If there is no buzz on other inputs then the issue will be somewhere in the turntable.  Check its power supply.  Is the buzz there when the volume is up but the TT not running?
Does the GR have the built in ground??

   Unscrew the headshell, , check to see if the little rubber washer is ii between the back of the headshell and tonearm?

  The GR may be so much better they dont use them in the uber high expensive model .
check the ground wire connection under the turntable- make sure wire contacts the terminal and not insulation- same at the preamp end. 

try shielded cables from table to preamp if yours are not.  

what input are you using from phono preamp to amplifier?