Thanks Mohsin - that's very helpful
In my handbook it says nothing of the maximum capacity size the unit can handle. Crap or what!
The online version of the Composition Media/Discover Media manual (I presume the printed manual is the same), has the following specs for the SD card compatibility.
SD and MMC memory cards with the file systems FAT12, FAT16, FAT32 or VFAT up to max. 2 GB (gigabytes), SDHC memory cards up to max. 32 GB and SDXC memory cards up to max. 2 TB (terabytes) with the exFAT and NTFS file systems.
I'm using a 64GB SDXC card with no issues.