Most on-the-motherboard audio devices support the Intel High Definition Audio standard. Windows Vista (and later) includes a "class driver", hdaudio.sys, which should work with any such audio device.
Usually systems come with a vendor-supplied driver installed. This driver is designed specifically for the hardware it runs on (as opposed to being designed to the standard) and so it comes with additional functionality.
Occasionally, for troubleshooting purposes, it is useful to switch from one driver to the other... either to get the additional functionality provided by the vendor-supplied driver, or to see what happens if the class driver is installed.
Here's how to switch back and forth.
Type "devmgmt.msc" (without the quotes) to launch Device Manager.
Expand the "Sound, video and game controllers" node and note the list of audio devices. In this case, I have one audio device, and by the "High Definition Audio Device" name I deduce that I have the class driver installed. (If the device name included a company name, I would infer that I had a vendor driver installed.)
Right-click the device you want to change the software on.
Windows offers to automatically detect the driver that should be installed. No thanks, we want to pick a particular driver:
Windows asks where we want to look - do we have a set of driver files, or is the driver already in the list of installed drivers? In this case, we want to look at the list of drivers for this hardware that are already installed.
Windows shows us a list of drivers that are already installed and usable for this hardware. At this point you would expect to see two drivers listed: the vendor driver, and "High Definition Audio Device." (When I made this blog post, I was lazy, so I didn't bother to make a screenshot that showed two drivers.)
To install the class driver, pick "High Definition Audio Device" and click "Next."
"High Definition Audio Device" is a class driver, so you get this warning. Click "Yes."
Windows does its thing...
... and eventually tells you that it's done. If your audio device was in use, you may get the "you have to restart" message. Regardless, click "Close".
If you got the "you will need to restart" message, Windows helpfully offers to restart right away.
Make sure you're ready for a restart (no unsaved documents or anything) and restart either by clicking "Yes" or by using the Start menu.
When you're done experimenting, you can go back to the vendor-supplied driver by going through the same steps and choosing the vendor-supplied driver in the list of drivers.