I'm using these:
It supports exFat for storing/accessing music. However, you need a smaller card in FAT32 for firmware upgrades, probably to avoid sd card stability issues causing firmware to corrupt and bricking it.
I organised music by Root> Category > Artists > Albums
It supports embedded album art or a jpg file in the folder.
I have a few SD's already and just purchased a sandisk 128gb sdxc 45mb/s.
How van i tell if some of my other sd's are fat32?