You simply can't beat this podcast

If you wanna know trade secrets of some of the best heavy metal and rock engineers, this is def the podcast for you. You should also check out everything else these dudes are into. Nailthemix, Eyal Levi and Joey Sturgis' classes on creativelive. Get your fill of these dudes knowledge. It definitely improved all aspects of approach, setup, mixing, mastering etc. I can't recommend this enough!