issues with ground loop from DAC?

I have a ground loop noise occuring when I connect my Benchmark DAC 1___but it only happens with my tube amp--Rogue audio stereo 90 in play--does not happen with my
back up solid state amp in use. Seems like tube amp not compatible with dac---anyone else experience this??
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
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 notice the DAC uses a safety equipment ground..... For a test try a ground cheater on the DAC power cord plug and then check for hum.

Are you using balanced outputs on the DAC? If not that also may help if you can.

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