I have been playing around with the construction of multichannel (6 channels) WAV and WMA files in the new Adobe Audition 3 and just for the heck of it I decided to import a few to Vegas to see what happens.
Vegas reads them just fine. They import just like an AC3 file... even the LFE track shows up! I don't know about others, but this is a new one on me. I guess I sort of assumed you could only import stereo wav files.