I'd rate my overall knowledge of any of my hobbies as way above that of the average person (HT, flashlights, dirtbiking, cars come to mind).
I rated myself 'good knowledge', as I have a very good grasp of connections, I can make my own adapters or wires, I can calculate resistances to keep an eye on impedance issues, and I can -- and do -- assist friends when they're shopping for something AV, or if they say 'damn, my dream is to one day buy a Bose system', which I heard 2 times in the last few months.
One thing I haven't done yet is use my new-to-me Radio Shack dB meter, and DVE disk to calibrate things.
Matt in Bowmanville, Ont.