I'm not sure if you are still looking for an answer,
(been a while since you posted). I'm not an expert, but
here is my best guess. I bought a Rio Forge player that
uses an SD expansion card. In most players built today,
they are just that, an expansion of the built-in memory.
When the built-in memory gets filled, the overflow goes
to the card. Therefore, it is probably not compatible
with other players. Most new players also come with their own software to load the songs. There is probably some other formatting on the cards that is particular to each brand of player.
If your old SD cards do not work with a new player, they can be re-formatted and then re-used.
Hope this helps.
I have a Panasonic MP3 player from a few years ago that uses an SD card. It came with a USB device that you plug the card into, then load in files through RealOne player. (I think it is converting them to MP3 when loaded.) We'd like a second player (for my husband) that lets us use the same device and SD cards so we can share cards. Since Panasonic doesn't make this anymore, can I buy any other player that uses SD cards, and load them with the Panasonic USB device? Or is it formatting the card in a way that wouldn't be compatible with another player?

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