There were some nice surprises in the 842. I could sync up the micstasy to the 842, and run its digital output to an 842 input, which could be set to stereo, so I could have a combination of 8 signals from the analog or digital mics that come out the adat output on the 842 and go to the motu traveler adat input, which is just being used as a headphone mixer.
One minor issue I had was getting that adat connection right, since I haven't used that before. I learned that the little adat cable provided needs to have some little clear plastic tip covers removed. Also those little plastic flaps on the adat jack covers apparently need to come off, according to someone at a local store, so I popped them off with a safety pin. There wasn't anything I could find in the manuals about either of these setup issues.
I ran the 8 channel aes output to a tascam aes to tdif box, then its tdif output into a tascam da78hr. I couldn't get the tascam to sync well to the aes inputs, but I guess that's their problem. I had to go the other way around, and use the word clock off their aes converter box to provide the sync for the micstasy daisy-chained to the 842, and then sync the aes converter box from the da78-hr tdif input. That was the only way I could find to get everything stable.
Anyway, this all is a pretty stable setup that I can use for recording, although I think I'd prefer to have either the micstasy or 842 provide the master sync.
I'm very happy with the 842 and micstasy operation, and I think I may prefer the sound of the micstasy with some of my old mics to the these neumann km184D's and their omnis, so it is nice that the two units seem to work together so easily.
btw, full compass sells those fixed frequency kmd mics at different prices for 48khz and 44khz, but you can buy whichever is cheaper and use the rme 842 box to modify their frequency. I thought it was really funny that the full compass b-stock 48khz mics were actually unopened 44khz neumann mics that they had mislabeled, so if it weren't for the 842, they would have been returned.
I'm shopping for an improvement to the da78-hr. I've been using Samplitude for many years, and I've never had problems with it at 44khz. I think the pcs are probably fast enough now so I could use the aes32 up at 96khz, and then run the aes straight in and get that aes-tdif converter out of the luggage.
Other than a homebuilt Samplitude box, I've read the comments about tascam x48 box. I don't get a good feeling, reading their forums, that it is any more stable than a homebuilt pc based system. Also, the forums and release notes say it really doesn't work at 192khz, as advertised, so you have to wonder if it is a partially completed project. Also, it appears the x48 tdif 96khz support is something recent, and their aes interface cards only go to 96khz, so it isn't clear to me how they even test out 192khz that was in the pr.
On the homebuilt box ... I'm leaning towards some fanless card design, and then adding a 128gb ssd for recording. These samsung/ocz drives were tested by tomshardware and appear to have a constant high record and playback speed across the whole disk.
This low noise designs uses one of the new p5q motherboards, which also appears to have a hardware raid card built into the board, in addition to the chipset ich10r raid. Maybe a couple of 64GB ssd drives in a raid 0 on the builtin hardware raid would provide a high constant throughput, low cpu overhead recording solution. I think I'm going to get that board, a couple of 64GB ssd drives, and one of their suggested low noise cases and see how it does with samplitude and an aes-32 rme card.
I've got a question about the optimum operation of the 842 with long lengths of aes cable. Is there measurable degradation of the mic clock stability or other mic performance as you increase the length of the aes cable between the 842 and the mics?