@emergingsoul -- agree. I think it offers some information but it's not a textbook entry on the subject. I think you're right to see that there's a fair amount of "Paul personality" mixed in with information. I learned some from these, too:
https://www.psaudio.com/askpaul/do-preamps-enhance-sound-quality/
https://www.psaudio.com/askpaul/do-we-need-preamplifiers/
https://www.psaudio.com/askpaul/understanding-differential-preamps/
https://www.psaudio.com/askpaul/why-are-preamps-expensive/
https://www.psaudio.com/askpaul/why-arent-passive-preamps-more-popular/
https://www.psaudio.com/askpaul/do-preamps-enhance-sound-quality/
https://www.psaudio.com/askpaul/do-we-need-preamplifiers/
https://www.psaudio.com/askpaul/understanding-differential-preamps/
https://www.psaudio.com/askpaul/why-are-preamps-expensive/
https://www.psaudio.com/askpaul/why-arent-passive-preamps-more-popular/