I have a matroska (.mkv) file that contains a couple AAC encoded tracks (5.1 channel). Is there a way to convert it to wav format so I can convert it to AC3?

I'm able to extract the audio track but can't convert it to anything after. (I used mkvtools, you can also use vdubmod).

Thanks!

Update: I've been able to get a stereo .wav file from using the aac winamp plugin and the winamp write to disk plugin. Unfortunately I'd really like to preserve the 6 channels and not downmix. Any suggestions?

Updatex2:
YAY!! I just merely imported the output wav file that winamp made into softencode and it appears to have six channels!!

Hope other people can use this post, I sure could have

Updatex3: Arrrggh, premature celebrating! The problem is I don't know which channel is which. Softencode just arbitrarily assigned a channel to each input channel. i.e. the lfe channel is the centre speaker. hmmm.

Updatex4: Arrggh, the outputted ac3 file is about 4 minutes out of sync with the video, why oh why?!

Updatex5: I ran the wav file first through besweet to change the freq. to 48kHz first, then ran it through soft encode. I hope it works