Even something like a Robert Harley's complete guide to high end audio is better than nothing. It's geared to the layman, very easy to understand, and touches on a variety of topics.
All the Nelson pass articles are great too.
I like dougs parafeed article as it really breaks down how a tube operates in a simple, clear, and concise manner - it was also Doug in his modding of my moth si2a3/45 h that really showed me how drastic the effect is of how a tube is loaded, in that case he CCS loaded the input tube and LED biased it which really improved things (as well as showing how limited even the best SET circuits are).