Get the latest vgmstream plugin for foobar2000. I added support for this a while ago. It also fixes an error that was present when playing mono .dspw files from Sengoku Basara 3. I guess I'll post an updated executable and Winamp plugin later tonight, unless someone else compiles it first.
I tested with foobar and it works, converted to wav 6 channel file surround. however, my question is the audacity output shows each channel as a mono file? is that normal? if not, how to extract each channel in original quality? thanks
Yes, it is normal. For multi-channel streams, usually the first two are left and right channels, then remaining channels are mono, but are usually in pairs. E.g. if a tune has 3 versions, it'll have 6 channels. For each pair, select the top track, and select Make Stereo Track or whatever it's called.