The PHILCO Phorum

Found one recently that helped me along with second revamp of my beloved Fisher 80.

http://audiophool.com/hifistuff.html

Surely there are more, and a knowledgebase of this stuff would really be nice to build.

Here are three more.

hifiengine:

http://www.hifiengine.com/

ElektroTanya (Hungarian site):

http://elektrotanya.com/

and, of course, the AudioKarma database:

http://akdatabase.com/AKview/

Thanks Ron, great resources are all around!