The iRiver original firmware does not work with any flash memory as far as I can tell, whether CF or SSD. It will not recognize it as a valid disk (you get the error message "Check HDD"). You will still get the OF operating, since it resides in the ROM of the device, while Rockbox resides on the HDD, CF, or SSD. But the OF will not read any data (e.g., play any music) from the SSD. I still like to switch into the OF for recharging, since it displays a nice big message while charging and when charging is complete. But that's pretty limited functionality.