^ SDPIF is always digital.
OT, but FYI the coax dig-in on the 680 can be used for two purposes:
1) recording a 1 or 2 channel SPDIF (coax/electrical) or AES/EBU format digital source.
2) sinc'ing clock of the 680 to another clock source without actually recording the signal.
1 also does 2.
2 does not require 1.
Most tapers will be familiar with 1 from using external preamps that have a digital output. I used to do the second when running both DR-680 and R-44 simultaneously so both machines would share the same clock (that of the R-44) and thus eliminate drift, even though the two recorders shared no recorded tracks in common. That way, using tracks from both machines in the same mix afterwards only required initial time-alignment between those made on one recorder verses the other, without any subsequent drift over a long recording that would ordinarily require time-stretching to correct.
