This is just to clarify make double sure that every1 knows exactly how to do this properly.
1stly use a decent HDD Formatting programme be it Windows or IOS or unix/ Linux etc...
Insert your new 64gb microSDXC Card into a decent card reader & then indeed make sure that U Format it to the FAT32 BUT PLEASE DO THIS PART AS IT'S MOST IMPORTANT THAT U DO.
FORMAT THE CARD IN FAT32 BUT MAKE SURE U MAKE THE CARD A BOOTABLE CARD, SO TO DOUBLE MAKE SURE THAT U UNDERSTAND = MAKE THE CARD A BOOTABLE FAT32 CARD WHEN U FORMAT IT, OR IT WONT WORK CORRECTLY.
& As mentioned take out the card from the C4 & use a reader to transfer your .wav/ .flac or even .mp3 files to the EXT Storage card.
Also can I recommend to U that U do try & leave about at least 10‰ free space on any storage device, that's my Ex Network Admin brain just giving U sound advice, sorry I just can't help it LOL
Anyways happy 96gb (well roughly 89gbs after the usual slight gbs loss U get) & it allows for a lot more hidef song files for this amazing quality player, I for 1 have been using my C4 Pro with a 64gb card for a while now & can't wait on 128gb micro cards
Happy Listening all