Well, my client approved of my answer. He responded that he had returned from the dentist and my answer was the first smile he had that day.
However, you are correct that my flippant answer is not suitable in all cases.
For example some vacuum tubes probably should be used only in a vertical application. We know that many small signal tubes, such as the 12AX7 and 12AT7, which do not run all that hot, seem to provide fine reliable service mounted horizontally. However a really hot running tube such as the 6N1P and most power tubes likely will not like long term horizontal use. The internal structure is designed for vertical operation. Horizontal operation of a very hot running tube may cause the elements to slightly sag, either changing the electrical characteristics of the tube, or worse case, causing it to fail.
I knew my client was referring to an all solid state cool running Insight DAC so I felt that an April 1st response was appropriate. I would not have given him the same advice regarding a Transcendence Eight or Ultra DAC, both of which use 6N1P tubes.
Regards,
Frank Van Alstine