Sure, the psychological aspect is some part of it. The sound of a good pure tube amp (and there are plenty of not so good ones) is appealing for a good reason. Solid state amps distort primarily odd order harmonics. Even distortion that’s barely measurable on a SS amp can be distracting and annoying to the ear. Tube amps, while having a total harmonic distortion much higher than SS, they tend to be much lower on odd order distortion, and do so more on even order harmonics. Not only do most people find this less objectionable. In fact, this is why most every rock or pop guitarist use tube amps when overdriving for the "fuzz" sound.
Are tubes psychological?
This just occurred to me this morning as I listened in my rather dark listening room with the soft glow of tubed amps on the floor in front of me between the speakers: How much of my enjoyment of tubes gear is due to the relaxed state the glow puts my mind in?
Thoughts?