I've been using Sound Studio on an old mac to do the mixing. That lets me paste any % of any channel into another, but it doesn't let me turn the knobs in real time to, say, add a bit more omni into a card source while listening. All I can do is know what I want beforehand and make the mix then listen back and see how it sounds.
I can't seem to get the mix I want out of these, but all I can do is paste various % amounts into other amounts and see how it sounds. What I WANT to do is have a program (that works on a mac) that I can load all 4 stereo channels into and then turn the knobs to the amount I want to hear from each channel and finalize the mix.
^
Just posting to confirm that is what you
really need to do when mixing multiple source channels. It's absolutely critical in my opinion. Jump on a multitrack editor such as Reaper or Audacity or something else as suggested. Connecting your ear to your knob turning (err, mouse-moving) hand in real-time will make all the difference in the world.
As a kind of desperate measure, I was even thinking that if I had a unit (I was thinking an F8) that would allow me that option on playback, I could just mix it down after the show and record a final mix in real time to through the line-outs, but that seems wrong in this day and age. There has to be a software solution.
Yes, the best solution is a software multitrack editor, but nothing wrong with doing via the hardware you already have. I do this frequently when I don't have an editing machine available (currently).
I use my OCM R44 to mix down 4-channels to stereo and record the SPDIF out to another machine. This provides "real-time" level control of all four channels. Unfortunately it does not allow for panning. Channels 1&3 are always routed Right and chs3&4 are always routed Left. Exception is if using the Mid/Side playback effect on one or both channel pairs, which pans ch 1 and/or ch 3 to center. You can then either ignore its channel pair (100% Mid) which lets you do a 3 channel L/C/R mix to stereo, or to use channels 2 and/or 4 as side channels, routed ti both Left and Right with polarity inversion to the right side. Alternately you can use the EQ or other functions instead of Mid/Side but they cannot alter the ch1 and 3 hard-Left, ch 2 and 4 hard-Rght panning.
I also do the same with the Tascam DR-680. It allows for panning and level control over all 6 channels in the mix down to stereo, was well as Mid/Side decoding on channel pairs, but provides no EQ. Like the R44, the DR-680s stereo output can be analog via the RCA line-outs or headphone jack, or SPDIF.
If you record the SPDIF stereo output from either of these machines you've not done any DAC/ADC conversions. The signal path through to the stereo mixdown file remains digital.
The Zoom and Sound Devices recorders provide more monitor/mixdown controls, with control over level, pan, mid/side, EQ, polarity, and delay I think per channel. I think all of those are limited to 4 channels out only, but that's not a limitation for mixing to 2-channel stereo. Some don't have a digital output (I don't think the Zoom does) so you'd need to output analog and re-digitize that, which is probably fine. Not sure if they allow mix down
within the machine to their
stereo file from the individual ISO tracks after the original recording has been maid or not. If so that would be the way to go if doing it this way. The DR-680 cannot do that.
This all works fine, sounds fine, provides the needed capabilities, and is fun to figure out, but is not nearly as flexible as a software editor. Its nice to be able to do this in a pinch, but a software editor is the best answer.