Yes, I had weird interactions as well. I put in new setup of tubes. They sound noisy. Flip them around and it goes away. LOL ...It's funny. After the kids turned the TV off I could hear a very slight hum with the Mrs X adapters. Very quiet but kind of like the noise it makes when you touch the end of a RCA cable with your finger when it's plugged into an amp.
Plugged Deyans back in and the feedback sounds more like tube whoosh...swapped them over and now Deyans are silent.
I guess I'll leave them alone and stop fiddling!
They are almost living things these things.
Need to start a seance ...