For anyone interested in accessible digital playback dvices, the following link is a review presented at the 2004 CSUN
http://www.nfbnet.org/digital.
As a side note, the Daisy format which was originally developed to be accessible for readers with disabilities, has split off into six different flavors of Daisy, not all of which play on all the playback devices, so if you are searching for an accessible playback device, you may have to choose the one which is capable of playing the specific Daisy format you want.