Isn't XMA like WMA 9 pro though, so what if we tried some WMA 9 pro tools?
I tried with ffmpeg's WMA pro decoder; even after reconciling the stream container (packet and frame) differences, it didn't work. My current idea is to poke at the Xact encoder until I can see how it is putting together the XMA stream, and then try seeing if I can relate those to the elements of the wmapro stream. They have some things in common and I hope it isn't just superficial. For one thing a lot of things are fixed in XMA that are determined by the stream in wmapro (like how the subframes are divided up). Couldn't figure out how to work that out yet... With luck it'll turn out that I just have to assume some parameters and then it'll just work, but I got frustrated and rather than drive myself away from vgmstream altogether I'm letting it rest.