That would be a way to do it, for sure. I'd like to be able to turn off the sending of the additional 12 channels, but I haven't explored that possibility yet in the XR18. I'll test the unit using just the first six channels to see how that works, as I'm unsure that what I might get in 'channel 1' is a sample from input 1, 7, and 13

Meanwhile I think I'll brush up my 'c' skills and think about writing a small program to grab the output from 'arecord' and demultiplex it on the fly.

@AaronD

The rebooting part bit me on a mission trip as we were packing up to fly home and one of our team wanted to record a testimony with him and our local translator. That was before I had my current system and so I ran the USB directly to the FOH laptop in 2-ch mode (2 mics) and recorded in Audacity. It took a while to figure out why it wasn't working like I thought it should, as we were trying to pack up and catch an international flight.

Now the system works as intended and I can capture the live one in front of an audience, as well as the music and whatever else we did, all in multitrack to remix later if someone was so inclined.

Anyway, you're not stuck with USB 01-18 being raw mics 01-16 and final FOH like I have them. You can re-patch all of it, and in fact I do that quite extensively to organize the channel strips for me and the front panel for the stage-setup guy, independently of each other. You can do the same with USB, also independently, and it doesn't have to be raw or final either.

Demuxing on the fly would be nice! Makes for less work in post. As you can see from the question, I originally wanted that, but couldn't find how to do it. At least not without writing my own like you're contemplating.

But now that I have the system that I do, I actually kinda like recording to a giant monolithic block and then converting to WAV later. That way I'm not limited by the file size and I know I have it all. If the recorder panics about 6.2 hours into an all-day recording (4GB mono 32-bit WAV file), then there's nothing I can do to get that back. With the monolithic block, at least I know I have it and I can try some other way to get it out.

@CharlesGreen I'm not sure if this tag is really necessary to alert you, but since you did, I figured it can't hurt.

@arron Success!

Grab the input from the A/D, pipe it through Sox, use remix to get only the channels I want and then... encode as w64 to avoid the 2 (or 4) GiB problem!

I tested my command (above) for approx 20 seconds on the XR18:

I was able to input the resulting 6 channel file directly to Ardour, and it seems to have worked well. Since my son's band practices only twice per week, I'll give that a shot next Tuesday.