Could you try the simple test that I just described in my previous post?
Printable View
Sorry if was not clear enough.
What I describe works with Vista and Windows 7.
Go Control Panel and choose Sound. There, your devices are listed. Mine is Realtek Digital Output.
Double-clicking it brings you to its properties. Choose the Advanced Statistics tab (my OS is in french; it may be a bit different in english).
There you have Default Format settings that you can test. You have 16 bit 44100 Hz, 16 bit 48000 Hz, etc.
When you click Test, it plays a sound in that format. That's it.
Forgive me for asking in case the answer is obvious, but why are you adjusting the speaker settings for your PC? Is your PC operating system unable to automatically detect the bit and frequency format of an audio file when it is played back? Or are you selecting say a 16bit/44.1KHz file, and then trying to play it back at 24bit/96KHz?
Not sure if running this would help for diagnostics - http://www.thesycon.de/deu/latency_check.shtml - dpclat - DPC Latency Checker. Might be completely irrelevant of course, but on my system it does show up some pinch points.