Since installing P3D version 2.1 the ability to adjust sound for GSX has gone! When I open the Coatil Products GSX menu and select audio, even if I do not make a change, GSX will not run and the only way to get it back is to restart P3D.
If I do make a change GSX stops working and upon restarting P3D the sound is not adjusted.
Problem doesn't happen here, and nobody else has reported it before. The most likely explanation is a bug in your audio drivers, that have problems supporting OpenAL, which is the sound engine we use for GSX.
The only possible suggestion is to update your audio drivers. Try with different solutions: using the drivers supplied with the audio card or the mainboard, and also try the opposite: remove any audio drivers supplied separately, and only use the one that comes with Windows. Sometime one solution is better than the other, but you just can't say for sure until you try, because it changes between audio hardware.
The problem is, the sound of the ground service crew (not vehicles I have removed these sounds as they too were very loud) is overwhelmingly loud. I am suspecting it is a P3D problem as AI traffic is also very loud and I am unable to adjust the sound levels.
Yes, it seems to be a P3D problem, it seems that it handles objects sounds in a different way than FSX, and also adds its own sound for vehicles that you can't control it. However, it's seems that is also related to audio hardware uses, because some users reported sounds being "too loud" in P3D, but I can't reproduce it. Yes, they are a *bit* louder than they were in FSX, but surely not "too loud", let alone "overwhelmingly loud".