Digital to Analog Conversion is the reverse process of the Analog to Digital Conversion. (Read up on Analog to Digital conversion.)
In summary, the binary numbers of digital audio are translated back into an analog signal. A DAT machine, MO Drive, sampler, compact disk and DVD recorder, all use the same conversion process. Used in a digital audio workstation, the translation from your hard disk is very accurate. It is resistant to errors (i.e. tape hiss, distortion, etc.) that converting to tape is prone to have. This makes digital audio conversion from hard disk the most convenient method for converting an accurate translation. However, it is important to mention that the sound quality of any of these methods of conversion is primarily based on that of the Digital/Analog Converter.