I'm using a DAW with ADAT outputs to an apogee rosetta 800 and a DA16 to give 24 tracks, running into an analogue mixer (mackie 24:8). I think I understand why it is important to sync up the three digital devices with word clock if they are running into a digital mixer for summing, but with an analogue mixer, does it really matter if the samples arrive slightly out of sync? I cant see how I would hear the difference, but that might just be my inexperience.
I also have a few digital outboard effects, should they be sync'd up?
If you picture your digital gear as forming digital islands, and you connect those digital islands with analog connections or analog processors and mixers, then everything on each island should by synchronized, but the islands don't need to be sync'd to one another.
As I understand it, you are "fanning out" to separate D/A converters. Word clock isn't needed here. It's when you're "fanning in" from separate A/D converters and other digital sources that you would want everything sync'd with the word clock.
1. Any time you're sending data from one digital device to another, both devices must be clocked to the same source. If you're using three devices, all three must be clocked together. Otherwise you'll get clicks and pops.
2. The analog mixer doesn't care whether they're locked together.
3. Sending Apogee converters into a Mackie analog mixer is - no offense, because it was a killer product in its day - pearls before swine. You'll be much happier bypassing that mixer.
4. I don't know what digital connections you have on all your gear, but using lightpipe for sync is not a good idea. It's great for data, as long as you run a metal wire for sync; lightpipe is very jittery, especially across longer distances, and you'll hear that. As I keep saying, ADATs sent sync down a 9-pin cable, not lightpipe.
As for the mixer, I rather like it I prefer the eq on the desk to the digital eq in the DAW and it's a lot easier having the faders, mutes and so on laid out in front of me rather than in a window on the screen, and I have a lot of outboard hardware I wouldnt be able to use without one. I'd be interested in what desks you think I might prefer to the mackie though.