Gearslutz is okay, but the topics are for more amateur IMO. I think best sites/forums to talk about recording audio are the tapeop forums and electrical audio tech forum. You must be warned though, they (generally) have an "analog is better but I embrace digital" mindset.

http://messageboard.tapeop.com/

http://www.electrical.com/phpBB3/viewforum.php?f=5 (You can argue with Steve Albini on here :)