I just turn my speakers to the level I do for just about any game I play, then make the audio a good level (Probably a bit quieter than you think it needs to be). It's still sometimes whacky ingame, so I just come back and alter the files if need be. Then again I hand alter a huge amount of it, as I get lines in from 31 different people and, as you can probably imagine, they are all different volumes.
