I'm looking to learn more about tube amplifiers. I have some background in electronics, and have a fair understanding of the topic. I've read books like Dave Hunter's Guitar Amp Handbook and Tom Mitchell's How to Service Your Own Tube Amp and found them too elementary. So I'm wondering if the Kevin O'Connor's The Ultimate Tone series would be a good set of books to get. One thing that puts me off is they are damn expensive and also it seems they are not really in order, so I'm not sure which ones to buy first. Would you recommend The Ultimate Tone books? Are they worth the asking price? Which books would you recommend? Morgan Jones' Valve Amplifiers book also looks interesting, though I don't know which would serve as a better next step. The current goal is to gain a level of understanding to basically know the function of every component in classic amp circuits. Where I'm at now, I have a good understanding of all the sections of an amp and how they work, but I'll often wonder, "what's the purpose of THAT resistor or capacitor?" P.S. I recently read John Rider's Inside the Vacuum Tube, and though a lot of the information in the beginning was very basic, and throughout the book he repeats many ideas, overall it did increase my understanding of tubes. It's a great book.