There is also a lot of good info at the "Acoustics" forum on AudioCircle.com, as well as some of the other hi-fi forums.
Room Treatments
I don't really know anything about room treatments. I have done some reading but still confused. I guess my main question is how does one know if they need absorption or diffusion? I have a tv hanging on the wall behind my speakers how does that effect things. Am I better off going with traditional panels and traps, or should I be looking at resonator devices?