There was a WMA player update as of January of this year (or at least its the most recent compile of it..
you can get it from the Player Files of the Volvo..
just can just update the phatwma and phatwma.sig on your phatsys partition.
http://phatbox.sixpak.org has the firmware files for all the various boxes out there.
The headunit files are the ones that change how your system works so DONT mess with that from another type of head unit okay folks?