Ayre QB9 DSD buzz

I have recently upgraded my QB9 to DSD. It has been running now for about 3 weeks. I can hear a hum/buzz from about a yard away.

I have tried it in different rooms, different mains cables, reversing the polarity, conecting to a mains filter as well as an issolation transformer, and even a different country, without anything making a difference.

I would like to ask if anyone else who has had an upgrade has had a similar issue? It didnt have this issue before the upgrade so I am wondering if it is "normal" or not.

I do not have an official dealer in my country and I needed to re-export and re-import when I had the upgrade. So I wanted to see if others have a similar issue before I go to this additional expense again.

Thank you

No issues here. Maybe try a friend's home to double check that's it's not a power line or DC on power line issue?
Thanks for your reply Nkbg
I did try it in another home, with the same result. I sent it back to the dealers and they agreed the buzz was unacceptable. What they feel is that as we need 230vac over here this means a larger transformer is required which might be exacerbating the issue. Anyway, a new transformer is on order which should hopefully sort it out.