I run two with a V3 and a USBPre-2. The Pre-2 will sync to the spdif from the other deck giving me a full 16 channels of clock synced recording.. If you don't use the pre-2 for sync and you don't have any preamp with digital output(AES/SPDIF) then you can get 12 channels of clock synced recording. You will still need to align the start of the two different decks in your DAW but then they run perfect together
Can you expand on this explaining exactly the connections? I have a V3 and Ua5 that i would like to use to link 2 DR-680's to achieve 16 different clock synced channels.
Sure thing, however I've never used a U-A5. Does it have an digital input like the AD2k+? To make a better example, let's assume you're either using:
Setup #1) 2x DR-680s + any outboard A/D - Will give you 14 unique tracks
OR
Setup #2) 2x DR-680s + AD2k + V3 - Will give you 16 unique tracks
Setup #1 is easy-as-pie. Just take the digital out from DR-680 #1 and route it to the digital in of DR-680 #2. This gives you 14 unique tracks (12 analog inputs aka channels 1-6 on both decks) + 2 digital input tracks on deck #1. Deck #2's digital input is recording the mix output of deck #1, which is where you 'lose' two tracks.
Setup #2 is also super easy, assuming your back can haul all this equipment to the show.
With this setup, the sync occurs by taking a spare digital output of the V3 and running it to the AD2k+'s digital in (sync in). Doing this clock syncs the AD2k+ to the V3 and subsequently both DR-680s become clock synced w/o losing any channels. You could also do this with a USBPre2 or any other outboard A/D that can accept a digital input to clock sync.
It's really a shame that the V3 can't sync to an external clock source; that's probably the one missing feature that keeps me from buying one.