I've got a book here called 'the Live Sound Manual' and I've read it. Let me tell you man, if you've started taking your trusty PA engineer for granted then you've got to start using lube again because there's a lot of knowhow that goes into getting a decent sound. It's incredible the amount of stuff you've got to know. Even for a small venue - I'm sure we've all experienced a terribly mixed sound at a small bar. It's all experience, ear and knowledge of the equipment. If 3 quarters of the amateur bands I've seen live had had a decent mix I'm sure they'd be a lot farther than they are today. It's an art as much as anything.