You are assuming GSX uses the .OGG format, which it doesn't. It uses the standard Windows .WAV format, because even if it's not compressed, *because* it's not compressed, it's the most lightweight and require the less possible CPU time to decode.
However, if your app needs to "replace on the fly" sounds from GSX, it might not work, because sounds are not necessarily read immediately before the are played, some of them are, others aren't, so you can't rely on that.