Audio Research Refernce 75se

It should be fairly quiet, especially from your listening position.  If you hear it from your listening chair (or further than a couple of feet away) it could be abnormal. 

A small amount of noise is normal but it shouldn't raise your noise floor noticeably.

The noise isn’t transferring to the speakers from what I heard.

cant hear it from where I sit. But 1-1.5 meter away I can.

It is NOT normal BUT…how do you know the buzz can be traced to the ref75se? Could be the pre, the power, the source, the turntable, the refigerator, the phono stage. Was the system fully balanced and wired with xlr cables? Were they using xlr to rca adapters at the ref75se? You dont have enough data yet.

System was really high end all around . @ghasley 

you can hear the noise clearly coming out of the amp

its small buzz/hum , even can say sound a bit metallic .

Probably why the party in question wants to sell it. ARC is subject to as many problems as any other brand but cost x times more to repair.  No practical experience, just my impression to what is written here.  

Next someone who has had no problems will chime in and say otherwise, and that's ok.