Of course there is! Avisynth!
1. Delete the default directsound device from your graph, then save it eg. audio.grf
2. create text file: eg. audio.avs with the following row (of course you modify the fps value):
DirectSoundSource("audio.grf",video=false,audio=true,fps=23.796)
3. open this avs file in MeGUI and encode it ...