Microsoft has included XAudio 2 in the August 2007 Direct3D 10.1 Tech Preview.

MSDN DirectX downloads - the latest SDK includes XAudio beta

From the SDK page:

The August release includes Beta 1 of XAudio 2. XAudio 2 is a new cross-platform audio API (Windows and Xbox 360) that is based on the Xbox 360 XAudio API. XAudio 2 is a low-level audio signal processing library for Windows XP and Windows Vista providing a fully modern audio pipeline, including:

• Multi-channel and surround-sound support with full per-channel volume and mapping control
• Programmable, cross-platform DSP effects framework
• Per-voice filtering, arbitrary submixing, and multi-rate processing
• Multicore optimized, non-blocking API design
• Pluggable and generalized 3D spatialization support, with a full-featured implementation provided by the independent X3DAudio math library

XAudio 2 is designed to be the game-audio API that will replace DirectSound.

Read more about XAudio 2 on the Microsoft Connect XAudio 2 FAQ page.

Seems like I won’t be uninstalling my RME ASIO drivers just yet.

Link via CDM