I don't think so, I don't have surround speakers so I'm pretty sure I put it on stereo.
I also have to turn my volume way up to actually hear anything in iRacing, so when I go back to Windows the volume is like 2 or 3 times as much as what it usually would be. PMD do you have that problem too? That isn't a huge problem since I've gotten into the habit of adjusting the sound going in and out of the game, but I wonder if certain sound cards just don't play nice with iRacing. I've got a SoundBlaster Audigy 2 ZS, for the record.