Does the Xonar Essence ST support EAX on Windows® Vista?Yes, Xonar Essence ST supports EAX2.0 on both Windows® XP and Vista through the innovative DirectSound3D Game EXtensions v1.0 (DS3D GX 1.0) technology.
Why do I need Dolby for PC games?•Dolby Digital and Pro-Logic IIx are available on the latest game consoles, like XBOX360, PS3, and Wii. Dolby provides the best gaming sound experience and compatibility with home theater or TV systems.
•Dolby Headphone and Dolby Virtual Speaker are the best 3D sound positioning, spatial modeling and 5.1-channel virtualization technology for regular stereo headphones, speaker headphones and speakers.
What are the most important benefits of the Xonar Essence ST for musicians?•Ultimate Fidelity: Xonar Essence ST has the highest quality of audio in/out for the cleanest sound production.
•Duplex HD: Supports audio sampling rates up to 24bit/192KHz for all inputs and outputs.
•ASIO 2.0: Xonar Essence ST includes an ASIO 2.0 driver for low-latency, 
low-distortion music creation application.
Will PCM sound output through S/PDIF be limited to 2 channels even with different analog output channels?
The S/PDIF protocol specification (IEC-60958) only carries the 2-channel PCM data or non-PCM AC3/DTS data. Hence, when a user selects PCM output for S/PDIF, the Xonar sound card always deliver a 2-channel PCM data through the S/PDIF output port. For attaining 5.1 channel surround sounds, you can select Dolby Digital Live encoding output from the S/PDIF out menu, which allows the Xonar Essence ST to deliver 5.1 surround sound for DVD movies, and even stereo music.