I am an expert by no means but I do have a good general knowledge of how to set up an AV/Stereo system.
I voted Good Knowledge in the pole.
I can use a SPL meter to properly set up a 7.1 theater system and use it quite often with my Outlaw Audio 990/2100 combo.
I spend some time experimenting with speaker placement and room treatments.
Set up my entire HT by myself and this included a Panny PT-AE900U w/Severtson screen, ButtKickers, HD-DVD player, lighting system, and several other items.
I always look at upgrading speakers but haven't taken the plunge yet.
Just an overall fun hobby.