A fine book for everyone interested in audio amp design and electronics. If you already possess an advanced electronic education this book probably isn't going tell you anything new. But if you want the principles of operation of valves and transistors and their usage in audio amps presented in an accessible and engaging manner in layman's (almost!) terms you would have to go a long way to surpass this. JLH had a long and esteemed career in both electronics and journalism. He wrote many articles for wireless world and the other electronics magazines over many years. It shows... Recommended reading.