About the actual topic at hand...
I agree with the sentiment that both clean and distorted tones are greatly affected by tubes. After owning a solid-state Fender Princeton Chorus for 10 or 15 years and an all-tube Traynor Custom Valve for about 6 years, I've worked up a pretty good comparison between SS and tube amps. The clean channel on my tube amp has way more "punch", which I would say is another word for "wide dynamic range" or "high headroom" maybe. There is such a huge difference between a lightly plucked note and a pounded 6-string barre chord.
The same goes for the crunch channel on my Traynor, where lighter distortion settings yield a very wide dynamic range and thus more "punch". It's not as punchy as the clean channel due to the natural compression in the gain staging. But, as the laws of gain staging dictate, the dynamic range decreases very steeply as I overdrive each gain stage by increasing gain/volume. Then the nice compression of tube distortion replaces the punchiness.