I had the same problem with Team Speak and Crew Chief being way too low. What I've done was lowered the game's volume using the Volume Mixer (right clicking the speaker icon on my task bar). Then I had to lower Crew Chief to about half of the volume of Team Speak, so now TS the loudest, then Crew Chief followed by the games sounds. Wearing headphones, I can make sure that the game sounds are comfortable, and the chat and crew chief aren't loud booming voices of God. Too me, lowering the volume works better than trying to boost Crew Chief to 11 and then taking Team Speak to 12.