Your best chance seems to be to find a source to download ToWAV. We can’t help you with that. You may need to use xmash from https://www.hcs64.com/vgm_ripping.html before ToWAV will recognise the file.
I’ve tried ToWAV and it won’t recognise the files, and neither will xMAEncode, Microsoft’s own tool for xma encoding/decoding.
Xmash helped for some, but it spits out about 25% that are just 1kb files with no audio in them (VGMTool fared no better, but then it’s just a GUI for the same tools). Many of the converted files are temporally compacted (presumably to save space - XBLA titles had stringent regulations about game size, as I recall), so I’m probably going to call it a day here, but it’s irritating that those 25% can’t be converted at all.
I doubt that this will be much help to the original poster as they have not visited this forum in nearly 4 years, and Gale Andrews passed away in 2017.
However, I’m interested to know why you say the file is Wwise Vorbis.
Yes, I doubt the original poster will find this useful, but I was searching for a solution to the same problem and came across this forum, so I decided to respond with the solution anyway since someone else might come here one day from Google.
How I know it’s that format is because I had a file with the exact same “RIFFT WAVEfmt” thing, and I managed to convert it with ww2ogg.