As for resonance and vibration, I've neverheard that "tube amps are more resistant to this factor." I always thought they were LESS resistant, because of the glass tubes. That's a startling claim and I have never heard that before.
I have never heard this from anyone else either, just fits with logic, to me, simpler circuits, less components, heavy transformers, mass damping. Think about it, less stuff to resonate in electrical fields means less hash i.e subtle information. The vibrations I refer to are extremely tiny.
I had similar issues with depth and have been looking at this subject lately in my solid state system. I can tell you the changes as a result have been simply astonishing. Not a plug, but Critical Mass Systems footers for electronics and speakers have turned my world upside down. From cones and sorbothane in the early days to springs to v v expensive bearing based vibration control devices now, nothing compares.
Best wishes