Amp/Preamp Asylum

Tube amplifier hum

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This Post Has Been Edited by the Author

Here's what is, to me anyway, a weird scenario. I have a small tubed headphone amp that has a pretty noticeable hum no matter where and how I set it up, except for one position. The hum is independent of the volume, by the way, and is mostly relieved if I stand there and hold it. The tubed amp is connected to an outboard DAC.
If I have it sitting another amplifier, a solid state amp called a Beta22, that is not on but is hooked up, plugged in and connected to my cd player, the tubed amp does not hum in the least. If I even pull one of the interconnects out of the solid state amp (at the cd player end), which is not on, the humming in the tubed amp starts up immediately.
To add to the mystery, if I put the tubed amp on a different amplifier that is hooked up to the cd player, just as the Beta 22 was, the hum is still there.
Any ideas what is going on?

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