No. The .MIG file is obviously corrupted, which is why I imaged the drive with ddrescue and attempting to recover the .m4a files from that (.img ) instead.
If TestDisk will let you recover files after a formatted partition I guess I could give it a shot. However, the drive was not just formatted, Windows was reinstalled which could have written over the sectors with the files I'm trying to recover. Formatting a partition writes (or rewrites) the file system to the partition...If only a format is done then all files will be intact since only the logical "pointers" to the files have been deleted, but going an extra step further and installing an OS and other software on top of the file system endangers any data/files previously written to the drive, since the OS thinks that the space on the drive is available (due to the format).
but like I said, there's a chance at least some of them are still there. I'll let you know what happens with MagicRescue.
This is a lesson learned. I will never again reinstall an OS without imaging the drive first. Migration tools obviously cannot be trusted. Good thing this was my neese's computer
...She's a little more forgiving than a customer would be.