A system for selection by a user and delivery to the user over an internetwork transmission channel of selected audio data files at a delivery rate of at least twice the delivery rate for normal, audibly perceptible playback of an audio data file. The user registers the user's selection of audio material with a central library of audio and/or text data files, and a digitized and optionally compressed omnibus file containing the user's selections is prepared and transmitted to the user at a high data transfer rate. The user receives downloads the selected data files to a personal computer or to a portable storage and playback unit (SPU) that may store and play back digitized text or audio data, using a docking station. The user carries this SPU until the user has an opportunity to audio process and play back the text or audio data files in audibly perceptible form.