Well since it records in .wav format the largest file size is 2GB- I'm using a 2TB HDD with the RX for the after-afterparties and records with no problem at all, but every 2GB (around 2 hours 35min) chops into a new file... the same thing happens with portable recorders like the Roland R-26 & Tascam recorders- most computers cant' see a file larger than 2GB for post/audio editing. But 20 min should fit in about 195MB