Media Center 15 added event style WASAPI support, and MC 18 made this the default.
WASAPI support was first added to Media Center 13.
WASAPI is the recommended Audio Output Mode for Windows unless your audio device has a well-behaved ASIO driver, and it effectively replaces all legacy output modes including Kernel Streaming and Direct Sound. One of the other main benefits of WASAPI is that it provides applications with exclusive access to audio devices, bypassing the system mixer, default settings, and any typically any effects provided by the audio driver. Now I have iTunes sounding better then it ever has, not as good as the DLNA connection, and definitely not better the the Xonar's on board headphone amp feeding my AKG K240 MKII's using either jRiver or Foobar2000 but at least usable. It allows delivering an unmodified bitstream to a sound device, and provides benefits similar to those provided by ASIO drivers. I did A/B's between Direct Audio and Window Audio Session and the sound in WAS is much better. It is available in Windows Vista, Windows 7, and later versions of Windows. The Windows Audio Session API (WASAPI) is Microsoft's most modern method for talking with audio devices.
See also: Audio Setup and Audio Output Modes
