There is only one (BIG) audio track, regardless it’s in Atrac or PCM, or recorded with an optical or RCA cable or a mic (I tried all the ways). Name is something like ATDATA03.HMA. It’s in a folder named HMDHIFI, with 7 other smaller files. Perhaps there could be a way to open this big file and access the tracks... but it’s probably encrypted. The only thing I did not try is to upload music to the computer. I would not be surprised it would be very slow...