The manual seems to say 99 folders (01-99) with 20 songs in each (01-20) as the directory limitations for Technics files. I haven't done much with SMF files yet. The 8 Mbyte SD included should hold on the order of 160 songs. The average size of 20 songs is about 1 Mbyte from what I have been working with but possibly could be the size of a fill floppy 1.4 Mbytes. The device is becoming common place in some digital cameras and is available up to 512 Mbytes. For pure Technics format use you may not be able to use the card up before you run out of directories to put the data in, I would think anything over 128 MBytes would be a waste. The large format cards I would think are only fully utilized if you use SD Audio for playback of downloaded material much like a CD recording using the buttons to the left of the SD slot. in summary there are 3 kinds of music material you can place on these cards which are Technics format, SMF format (both digital instrument data e.g. MIDI) and audio tracks from other sources known as SD-Audio. Don't know much about SD-Audio yet.

Ron