Hi,Eitan, I did not sign the APO. I have set the DisableProtectedAudioDG registry value to 1 according the sysfx.doc, such as: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Audio "DisableProtectedAudioDG"=dword:00000001 Is this enough? Thank you! Best Regards, -------------- Jun Xue 2007-08-18 ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/