Game Audio Forum
Game Audio Forum has been around since 2006. With more than 1500 members it has the potential to have many interesting discussions. Unfortunately the amount of updated topics are scarce with a handful of people being active.
Game Audio Network Guild
As well as being the largest community in Game Audio, G.A.N.G. also has a forum. You have to pay a small yearly fee to get access but it’s well worth it. Instead of trolls you’re met by a helpful and dedicated community that’s not afraid to answer both beginner and advanced questions.
Gamedev.net is, as the name indicates, a forum for game developers. One section is dedicated to music and sound. Nate Madsen does a great job moderating the subsection which has a moderate amount of activity.