The Colibri PXA300 doesn't have a codec for audio and touch functionality. It is possible to add this functionality with external devices. For example you can use the AC97 interface which is available on the Colibri PXA300 SODIMM interface. By default the PXA processor provides a system clock which is used by the codec. However you could use your own clock source like an oscillator. In this case you can disable the system clock of the PXA processor with the following registry setting:
[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\AC97] "SysClkEn"=dword:1 ; 0: disable SysClk, 1: enable SysClk (default)
PXA300 XT comes with audio and touch functionality.