GPS:In the DVM-7400 and the AM-4 you usually had to put them into GPS mode using a DIP switch (except for the /G version of the DVM-7400). Is that the case with the DVM-8400?
No. The GPS input is a dedicated input that is separate from the RS-232 port. It is always on, and always listening for GPS data. No need for configuration. All you need to do is connect a GPS receiver, and start a GPS playlist.