I believe then it might be your Playback device then maybe have you got a headset you can set instead of the Realtek HD audio.
If this doesn't work i honestly have no idea mate. Hope it helps.
Not sure if these are the best settings for this headset but i can say i have not really experienced any problems with audio when using them and they have generally been good.
I have the same headset my sound feels fine would you like a screenshot of my Synapse? And just to be sure you are using Razor Synapse right? Because when i exit the application my sound goes all funny.
Yes the main reason i got my SSD was because when i played ARMA i would constantly get FPS spikes and drop to like 4 fps for about 20 seconds. I played on the server today for 4 hours and did not get one spike.