There are products you can buy which claim to eliminate ground loops; that cause hum to occur; such as the Ebtech Hum X. More likely than not, if this is sporadic or new behavior altogether from the Orchid DAC, it could mean a bad power transformer in the DAC. So maybe that would have to be replaced.
Are you using a power conditioner? Although it is true that all audio gear has power filtering modules and power transformers that clean up the AC and feed the parts/mainboard regulated DC, a good power conditioner can take the strain off internal power transformers for good...feeding each one clean electricity. This means audio components can run at optimal temperatures and may last longer.
Check out my profile. What I’m using works wonders. While some may disagree considering the low cost, I believe the practical application of technology and proper engineering/design are far more important than a high asking price, which doesn’t necessarily guarantee top quality or performance.