Not an expert here... but a suggestion... what I would do.
- Find a cheap expendable CD player... like the old generic diskman at the bottom of the kids toybox...
- play a CD out from that into your battery box, like it was mics, and record into your recorder. Yes, you are feeding 9V into the output of the CD player... which isn't a good idea, but I don't THINK it will fry the CD player short term. If I'm wrong, that's why I said use a cheap expendable CD player.
- take your recording and compare to the original looking for artifacts.