for now, use KSAUDIO_SPEAKER_5POINT1 instead of KSAUDIO_SPEAKER_5POINT1_SURROUND (according to http://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/SpkrConfig5.doc); maybe try the SURROUND one as a fallback
for now, use KSAUDIO_SPEAKER_5POINT1 instead of KSAUDIO_SPEAKER_5POINT1_SURROUND (according to http://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/SpkrConfig5.doc); maybe try the SURROUND one as a fallback