Paul, I'm glad to say there is a way to do what you want. Take a look at http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/directx 9_c_Summer_04/directx/htm/systempropertysets.asp. This only works in user-mode code, however. I have a code snippet demonstrating how to do this which I can send you directly if you give me your email address. Dugan Porter - DirectX Audio Team - Microsoft This posting is provided "as is" with no warranties, and confers no rights ________________________________ From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Paul Gryting Sent: Wednesday, November 30, 2005 8:48 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Direct Sound Question I have a wdm audio miniport driver based at one time on the AC97 sample driver. This driver will handle multiple device instances (via AddDevice) With Info from Richard Fricks, I was able to relate an application level open wave handle to an individual instance of an adapter for my hardware to utilize a private interface in the driver for an alternate control path. The problem is, so far I cannot find a similiar method to do this for a direct sound GUID. There is a relationship between DS enumerted devices and wave enumerated devices, so I was relying on that for the DS device. However this relationship is not garenteed, and is always wrong immediately after chaning the primary audio device. Does anyone know how to releate a specific enumerated DS device (identifed by DS GUID), to a specific driver instance for that device? (Or even a garenteed way to relate a direct sound device to its associated wave deviceID) pjg