Doepfer

Hello all . 

I am having serious humming problem in my modular system . 
I tried and still trying dozens of combinations and possibilities but in the end i couldn't succeed and wanted to ask some assist . 

I am using 4 x Doepfer A-100G6 housing . 

All connected to same power source and phase . 

I am using cwejman mx4s mixer connected to Cwejman AI2 than to Soundcraft Ghost which is my main mixing console . 

So far what i tried ; 

- connecting all the studio equipment on same power source (as a standart rule) : no change
- connecting ground points of 4 doepfer racks together : no change 
- connecting a part of chassis from ghost mixer to grounding point of doepfer cases : no change
- power regulator : no change 
- connecting same racks to my friends studio : no change 
- connecting power cables with reverse polar : no change 
- using DI box between Cwejman AI2 and Ghost mixing console : no change
- emptying racks completely and trying modules single by single : no change 
- connecting cwejman mx4s mixer to one empty case and connecting cwejman ai2 to the other case , or connecting them both in the same case : no change 

And as you can imagine i am a bit desperate at the moment , because i tried all the possibilities, and also suggestions from different people. 

I will be very happy if someone has an idea out of the things which i tried so far . 

thanks a lot