I'm not quite clear on what you're trying to accomplish. Here's what I
think you're trying to accomplish:
Send the V3 an analog signal (from mics, presumably, but could be other sources). Amplify that signal with the V3's preamp. (Do not use the V3 ADC at all; ignore the V3 level meters outright.) Send the V3's analog output to an outboard ADC that does not have input trim. Adjust accordingly using the V3's stepped and variable trim gain so the V3's analog output to the outboard ADC achieves desired levels.
Is this correct?
If so, you really only have two options:
- Run the V3 with internal input attenuator jumpers set to 0 (i.e. not attenuating), and use however much / little gain you need to achieve proper levels on the outboard ADC. I would expect this option to work if you're sending the V3 a mic-level signal.
- Run the V3 with internal input attenuator jumpers set to -20 dB, and use however much / little gain you need to achieve proper levels on the outboard ADC. I would expect this option to work if you're sending the V3 a line-level signal.
Unless I'm missing something, one of these two options should provide the results you desire. Am I missing something?