Interesting informations. But please do not make any assumptions about APIs in use like WinMM or Xaudio. Windows uses API wrappers for many things and it can be that some DLLs are loaded although the program does not use them directly. If you google after FF14 and WinMM then you will find many messages about winmm.dll which are some years old.

That the CPU utilization goes up when sounds are muted, this is also interesting. Rendering sound and then remove the rendered sound afterwards would be very bad programming practise. But since i have seen much source code of some "commercial" applications i do not wonder about something like this. It is called "technical debt" and if you do not pay attention to this it will overhelm you some day. I guess, SQEX is now at this point. Sins made in the past are now back and cost them real money. And they can not fix it quickly because it could break some other functionality.

Cheers