As per Dale himself says stereo will work via a pm to him
I'm going to answer you, TwinBoom, but don't get all revved up because of it.
Yes, stereo will work. Stereo is an input option. I tested stereo and discovered that the Doppler effects in the game create anomalies that sound terrible, and do not recreate any realistic event. However, you can adjust stereo to correct for the issues DirectX Doppler creates, but at the same time stereo sound, any stereo sound, is twice the size of the same sound in mono and offers nothing extra because the game correctly creates stereo, 5.1, and even 7.1 depending on your own system settings. So, stereo sounds merely increase the size of downloads, place extra burden upon your system while playing the game, and creates audio anomalies. Worse, when it comes to locating vehicles the position of vehicles is obscured if you are using stereo sounds.
So, rather than use stereo why not just create a richer mono sound that works correctly with the game and includes all of the audio fullness of the original vehicle, or aircraft? All it takes is recording a half-dozen impressions of the same sound from different distances, and angles, or more correctly to account for all of the physics and mechanics involved.
I'll just leave it there.