On the DM-620, can I rewind a file to a particular point so that I can insert, append or dictate over something I have just recorded?
No. Unfortunately the rewind buttons will not work while recording a file using the DM-620. When you stop a file using a recorder in the DM series, it will immediately start a new file. There is not an option to insert, append or record over data recorded. Note: You can pause a file and then continue recording Source: …