The guys over at XPS-Wiki have found a way to enable Stereo Mix on a Dell XPS M1730.

Originally, Dell reported that Stereo Mix was not enabled due to ‘hardware limitations’, however this mod provided by XPS-Wiki users (BatBoy & L33) has proved otherwise. The install process is simple too;

1. Download the original IDT audio drivers (R196492) from Dell.
2. Download the mod archive from here.
3. Run the original install from Dell to extract the files, but quit the installer prior to the real installation.
4. Locate  the extraction path.  The default is C:\Dell\drivers\R196492
5. Depending on your system configuration, copy the appropriate files from the mod archive (32-bit or 64-bit directory) and overwrite the ones in the extraction path.
6. Run setup.exe to perform the installation. (C:\Dell\drivers\R196492\setup.exe)
7. Finally, reboot when the installer is complete.

XPS Wiki reported that there is 100% compatibility, but some elements of the audio driver (such as Jack detection and surround sound) don’t seem to work on my system. However I am not overly fussed, more importantly, Stereo Mix functionality is now enabled on my XPS.

Thanks XPS-Wiki for the mod .