Documents -> My Games -> FINAL FANTASY XIV - A Realm Reborn -> FFXIV.cfg
There's also a FFXIV_BOOT.cfg config file here, too.
Opening the base FFXIV.cfg has some options I'm going to play around with:

<Move Operation>
Is3DAudio 0
BattleEffect 1
BGEffect 1
ColorThemeType 1
SystemMouseOperationSoftOn 0
SystemMouseOperationTrajectory 1
SystemMouseOperationCursorScaling 0
HardwareCursorSize 0
UiAssetType 0
FellowshipShowNewNotice 1
I'm going to set the Is3DAudio to 1 and see if that makes any difference.