Re: E6520 w/ XP - IDT Audio Control Panel
There are only two radio buttons showing on the main page "Power" and "Miscellaneous". There are no settings for equalization or HDMI or anything.
Without seeing a screen shot of what you have, it is hard to say. If you went
Start>Control Panel>IDT, then all you get is the power management configuration, which should be at full performance or similar for best audio.
For the IDT control panel, I think it is Start>Control Panel>Additional Options or something. (Not sure exactly -- I don't have IDT.)