Really?
Huh, I don't remember that, but I didn't do it that often and when I did I probably set it prior to hitting rec/pause.
In that case, can you work the cascade the other way? Then you should be able to change the DIN monitoring on the fly on the mk1.
You mention recording 12 channels total. Do you want to do this simply to confirm digital connectivity via the stereo channel meters? or are you planning on keeping the stereo mix file from the first machine which is going to be recorded on the second machine over the SPDIF connection and want to make sure it doesn't clip?
You needn't record the stereo channel on either machine unless you want to do so for some reason. As long as the clock of the second machine digitally locks with the first, the 6 channels recorded on each will be clock-synced with each other. If the master/slave cascade of transport functions works as well that's gravy. I ran the mk1 and an R44 together that way a few times for 10 channels.
Definitely switchable on the fly on the 680. I double checked after I posted. That whole menu is accessible, and isn't on the MKII. Also, FYI, it works with the latest firmware, and I know it worked with whatever firmware I was running in September of 2013, as I recorded a show with all 8 tracks then and I'm certain I was switching back and forth.
Let me explain the setup, so you can make some sense of it:
2 room mics -> preamp -> ADC -> 680MKII (DIN/stereo track)
6 instrument mics -> 680MKII (tracks 1-6)
mix of tracks 1-6 on 680MKII -> 680 (DIN/5&6)
4 line level feeds from mixer (vocals and DI) -> 680 (tracks 1-4)
That's the setup for 2 reasons:
1) In theory, the preamps are better in the 680MKII, so I'd rather have the mic sources get recorded by that and have the line level sources get recorded by the 680.
2) While I won't use it for mixing (other than to line the tracks up), it's nice to have the monitor mix from the 680MKII feed tracks 5&6 on the 680 so I can monitor *everything* (other than the room mics) at once on the 680. I could record DIN on the 680 to that stereo track, thus removing the need for the ADC and recording on the stereo track of the 680MKII, but then I could only listen to half the tracks at once.
I'll probably just do some checks on the levels of the room mics into the ADC beforehand, so I don't have to rely on the meter on the 680MKII, but it's still kind of annoying.