It should be possible - the built-in HDAudio system effects do this (for speaker virtualization). Forgive the basic question, but have you selected 5.1 output for your device in mmsys.cpl? Dugan Porter - Game 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 Jeff Claar Sent: Thursday, July 20, 2006 2:33 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] APOs and multichannel inputs Hi everyone, I'm developing an LFX APO that includes a multichannel to stereo virtualizer. However, on a 2 channel codec, I'm having trouble getting any multichannel input, even though the source is multichannel. Is it possible to get multichannel inputs into an APO (when the codec is stereo)? Thanks, Jeff