An old thread, i know, however this info may be useful for others experiencing this issue.
I had issues with the "SmartAudio 221" microphone driver on my Toshiba Satellite with Vista 32bit. I wanted to use Skype in particular.
This is a solution to the issue where there is hardly any microphone level.
(both the built in mic and the mic jack)
Goto Control Panel > Sounds > Recording Tab
* Double click the microphone icon.
(If there is no mic icon, then right click and Check "Show Disabled / Disconnected Devices", OK that then right click over mic icon and click "Enable")
Goto Advanced Tab
* Uncheck "Allow application to take exclusive control of this device"
Click OK, then OK.
It appears that Skype was auto adjusting the microphone level down to "3" for some reason.
(So it may not be the actual driver that is at fault here?)
In Skype
Goto Tools > Options > Audio Settings
* Uncheck "Automatically adjust microphone settings"
then i manually set the mic level at about 75%, click OK
I done a skype test call and it works perfectly again.