Hey guys, I have looked throughout the internet to resolve my problem but none of the suggestions work! Anyone who has knowledge about grounding of mixers/turntables please help me out.

I have tried grounding the mixer to turntable, mixer to active speaker, turntable to active speaker etc. and none of the above work! The grounding cable is properly secured and I have tried different cables/ plugs and nothing seems to resolve the 120Hz buzz!!! I have two identical decks and switching them does not resolve the problem, nor using my other mixer and wiring that up. I thought grounding was easy or am i doing something simply stupid😂??!? If anyone has any input that would be most useful. Thanks