MRHP, I'd recommend that you pick up this book (from Amazon or eBay..): "Elements of Radio" by A. Marcus and W. Marcus. It's old, but unique in that the 1st half of the book goes into the "evolution" of tube amplification and how all these "little tubes" came into play into the circuit of an audio frequency amp (and "radio detector", RF amps, etc.). Probably not all of Bob's "tricks" are covered, but the basic reasons for the "little tubes" pretty much is... Has an entire chapter on all the different types of tubes and their function. NOT a bunch of data and statistics on each; just the how and why of the different types. Also covers power tubes in // and push-pull. The 2nd half of the book delves into the math and science part of circuit elements, magnetism, electricity, etc., but they try and keep the 1st half more "words" and common sense oriented....
FR: 400 disk changer with PS Audio Digital Link III DAC; Technics SL-1100A TT. QED Quenx1 IC's from DAC & TT to Adcom GTP-602 preamp/Tuner. AudioQuest King Cobra IC's from preamp to M1.0t mk-II opt2. QED Silver Spirals 4M wires to EPI 1000’s.
LR: AudioQuest Black Mamba 8M IC's from family room preamp to Barcus-Berry 2002R Sonic Maximizer to GlowPower Zyxt IC's to Sunfire 300x2 to Nordost 6M bi-source wires to AOS 28" MDF spherical speakers using six 8" woofers and eight 1" dome tweeters symm. arranged around the surface.
SS system: CX-995V DVD to AV-634x 3-4 channel amp (center/rears) & M1.0t mk-II opt2(fronts).
Garage: 300 disk changer to Entech 202.5 DAC to MXR150 Receiver (pre) to TFM-42 to EPI 400 speakers.