At least the source files and player are both downloadable... but there's no MAME binary link that works =/ If I could get my hands on one, I'd definitely consider adding support in ProSonic for the new VGM v1.51 format update this guy has done.
saxman, I actually had you in mind when I bumped this thread, because I knew you could do something good with ValleyBell's stuff. I think you should try to contact him on smspower (send him a PM or something) and see if he's up to collaborate with you. I think he's doing his stuff in Visual C 6.0 so you two should be able to get along since you're using C for prosonic as well. And maybe your experience might even help him into making the format better or something. It's always good when two good guys work together so I'd say go for it.