I got a sound bug too, but i am only using stereo sound (though my X-FI soundcard uses it's virtual surround engine (or whatever its called) to let it sound like surround on a stereo headphone.
most of the time the sound is nice...but sometimes it sound as if you would here a sound over a telefon. it sounds scratchy and not clear. that happens sometimes when inside the C130...but most of the times it happens with Truck engine sounds.
it sounds a little bit, like broken speakers...when they got to play a frequency they cant properly. (i know its not my speakers...i got a really good headphone).
it feels to me, that the game sometimes got like only 8 sound channels...all of them are full....and ther next sound that comes just got pressed into an already used channel.
hope you know what i mean.