I also had a residual noise when I used your Atmashere amps. It is inherent in tube amplifier designs.
With all due respect, you really need to try this type of grounding before you comment. It would probably surprise you, as it did me.
Its true that tubes are noisier than solid state. But you should not get any buzz if things are going well- just hiss. I run my amps on horns and I'm not particularly keen on buzz, nor do I get any. There are a good number of things that can cause buzz in a tube amp- for example leakage in the filament/cathode elements of the tubes, where noise can be injected into the audio circuit, or swept resonance between the inductance of the secondary winding of a power transformer and the capacitance in the junctions of the power rectifiers (of course that can happen in solid state amps too). Neither has anything to do with ground!
You might want to look at this page; of particular interest is page 20:
https://docs.google.com/viewerng/viewer?url=https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
Grounding is a far more complex topic than most people realize! I love the comment he makes about grounding in aircraft, not having to drag a ground wire around- its a good point.
At any rate I'm not contesting that you hear a difference or that it might be an improvement! Instead I'm simply pointing out that because that is so, it points to something amiss in the grounding scheme of the equipment you're using. Its a common problem in the audio world; I've seen amps that are currently in production that have grounding schemes from the 1950s before grounded outlets were a thing; others that have IEC connectors but the ground connection isn't hooked up. I've no idea how such products could be shipped overseas, since they are a bit more draconian about such things in Europe and even China; relatively speaking in the US its a bit of the Wild West in this regard.