Unfortunately I seem to have really dirty mains, had a H590 on demo, which hummed and then a loner H390 again hummed and finally my new H390 which again hummed, definitely DC issues which the Puritan drastically reduced (great equipment shame about the price). The H400 seems to have a buzz and I am wondering if its from the secondary small transformer and I am betting it doesn’t get the same mains feed as the main which has the DC blocker and is quiet. So now I think the culprit is the small transformer that I think is used to power sundry stuff. The unit was an ex demo and will contact the dealer but will give it a few days, maybe will ping Hegel direct. When I put my ear close to the amp the buzz is on the right side as you look at the amp from the front which again indicates the small transformer - perhaps it is picking up DC that the Puritan isnt killing. The H390 hum was the big transformer and the H400 is silent in that respect so am convinced its the small transformer. @baconboy do you think the buzz is the small transformer in your unit, mine is constant and maybe its just "normal" transformer hum
