issues with ground loop from DAC?

ZD542--thanks--but not a big fan of cheater plugs
I am using An Audience line conditioner

I don't think your problem is because the Rogue is a tube amp (Unless, as Tsugury suggests, you actually have a bad tube). One thing you may want to try, even if it is only temporary, is one of those "cheater" plugs that bypasses the ground pin to see if that may help. Most likely, getting a line conditioner that isolates the components, will fix the issue.

I had a similar problem. I kept trying to find the ground loop to no avail. Changed the ic's from tube pre-amp to ss power amp helped (had been using unshielded). Came down to a tube going bad in the pre-amp. Changed the tubes and no more noise. Might want to try if all else fails. good luck