Paul... Thanks for weighing in.
I don't want to sound pedantic but my answer to your question is, "It depends what you mean by 'level'."
Thinking about this in a mixer context, each channel has a preamp gain (or 'trim') control and a fader, correct?
What I'd like to know is whether the MixPre channel knobs act as a) preamp gain controls; or b) faders.
Thanks,
dp
If you dig through all the posts, this has been covered, and the answer to your question is that it can be either. In basic mode, the mixpre only records 2 channels, and those inputs are routed to the LR mix. In that case, the channel knobs control gain and do not act as faders. In advanced mode, multiple channels (up to the full set of 6 input channels) can be armed, with a LR mix track recorded and each of the other six channels (if all armed) are recorded to ISO tracks. In the advanced mode, the faders ("channel knobs") only control the level of the recording to the LR mix track. The 6 ISO tracks are recorded post-trim, pre-fader: that is, the gain is set by the trim control (which appears to be the control knob on the side) not the channel knobs, such that the channel knobs have no effect on the recorded level of the ISO tracks, only the LR mix track.
If you wanted to record all channels but instead have the channel knobs control the level of the recording of the ISO tracks, you can set up the mixpre in custom mode, using the advanced mode portion that allows arming all of the 6 channels but instead choose basic recording as part of the custom mode such that the channel knobs control the recorded level of the ISO tracks. In this setup, the channel knobs act as the preamp gain (trim) controls not as faders.
That seems to address the function of what happens. If you're asking which of the actual gain stages within the mixpre are being used in the custom mode above (trim/gain stage vs fader gain stage), we'd need a block diagram or have Paul comment. I'd imagine though as the fader gain stage can only provide 20db of gain that if you choose basic record mode such that the channel knobs act as trim control, then the gain is actually applied at the gain/trim stage providing access to the full 76db of gain.