What channel mask are you specifying in your WAVEFORMATEXTENSIBLE? From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Bielik, Robert Sent: Monday, December 17, 2012 4:56 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Nvidia drivers & portaudio wdmks issue Hi all, I've run into a problem with Nvidia drivers, the behavior is as follows: I setup the HDMI audio output for 7.1, and I can verify in sound control panel that all channels sound correctly. However, if I open the Portaudio WDMKS device (WaveRT) with 8 channels, I can only get sound for channels 1,2,3,4 and 7,8. I.e channels 5 & 6 are silent (!) Any idea what might cause this discrepancy ? Regards, /Rob