A "reference system" is simply an audio enthusiast’s primary system that they use as a comparison (or a "reference") when auditioning new electronics, speakers, cables, etc. Being one’s "reference" does not necessarily mean the system is anywhere near state of the art/science.
I do not understand how someone with over 7K posts here could say they have,
never heard of audiophiles whose reference system had transistor amplification
Just check the virtual systems for an answer to your question.