Seems like the best "upgrade" for tube amps....

The human brains goal is to provide a stasis, both psychical and mental.
If you make a design at first to keep costs at a minimum, you will not only believe that is the correct course, but if you are highly invested in that belief the brain will not let you hear any difference. Not saying Frank or anyone did this.

The main reason not to lie is soon you will believe you own lies.

Interesting thought and one that causes me to reflect on my own beliefs and biases on all things audio. Thanks much.

Not original to me, just my words.
Brain research has exploded in last few years.

It is possible that Frank feels that there is no substitute
for good engineering, even expensive parts. Case in point I
purchased a cheap chinese preamp, called Modwright to have it
upgraded. He asked me what would you have me do to it if your
not happy with the sound in general, I did read between the
lines at that juncture and let it go. But there are good
products out there that do benefit from upgrades.

Someone once said something along these lines: The sound quality of a given component is 75% due to the circuit design, i.e. the engineering, 75% due to component part selection, and 50% due to build quality.

I like this not just because it's funny but also because it reflects the truth that a given person can focus intently on just one of these aspects and can improve sound quality significantly and then conclude that this is the most important factor. For example, a designer might spend lots of time trying different operating points with his tube circuit, or a modder might spend lots of time trying different capacitors, or a builder could try different layouts and different chassis materials. Each one will find that some variations are better than others and there may be even be a "best." But this experience does not mean that this one approach (circuit design vs. component swapping vs. build quality) is the only or even the best road to good sound. They are all obviously very important, and none of them greatly outweighs the others in my opinion.

From the other posters' comments, it seems Frank Van Alstine is mostly in the circuit design camp, but I am sure that even he would acknowledge that component quality and build quality play some role in the sonics.