[LAU] Analog and Digital Audio Signal Audio Info Resource?

Hi, I've noticed many posts on the list quoting ohm, K and other figures when refering to analog signals. Its making me realize that I know next to nothing about what's going though my wires as I record or patch. I do know about Hi-Z guitar connections, balanced connections, etc.. but just the basics not the specific details. The same thing goes for USB/Firewire/PCI interfaces. I keep on hearing terms like Bus Mastering and how USB devices have higher latency. I'd like to understand what these are and why this is. Does anybody know of a good online guide to walk me though all of this and explain the specifics and how it applies to audio. Google has not yield any good results. Thanks -Chris