I use:
A ZEDI10 mized
Two Behringer C-3 mics
A laptop running Window 10
My problem:
No matter how I set the levels, one of the two mics always produces a track that is quieter than the other. Sounds like the speaker is standing far away no matter how close they get to the mic. The levels on the ZEDI show that both mics are equally hot, so I don’t think it’s the mic itself that’s causing the problem (although it might be.)
I have already tried:
Plugging in ONLY the suspect mic.
Switching the inputs (m1 to m2 etc.)
Setting the gain on the suspect mic higher than the other.
Conclusion:
Again, the meters show that the suspect mic is hot (when I turn up the gain it goes into the red.)
Not sure if Windows is causing the problem or if the mic is indeed faulty.
Thanks in advance for your help!
I assume you have one mic panned hard-left and the other hard-right? And are you getting stereo with the sound from one mic on the left and the other on the right? (If you’re not sure turn the volume on mic completely-down one at a time.)
Switching the inputs (m1 to m2 etc.)
And what happened? Is the “defect” associated with the mic or the input-channel?
Your mixer is supposed to work as a 4-channel interface, but Audacity is generally only going to record 2-channel stereo. So, you might have to use channels 1 & 2, or you can probably configure the mixer to send the -2channel stereo-mix out-to the USB port.
Your mixer is supposed to work as a 4-channel interface
It’s not shocking that some interfaces record as stereo but don’t use the first two microphones in the interface. So there is that.
I would have been reducing everything to simple stereo and do tests that way. You already know from the lights on the interface that both microphones are working, right? One microphone makes the ZEDI10 Left meters blink and the other, the right.
Scene shifts to Audacity. The recording meters in Audacity are stereo. They should follow the ZEDI10. The top meter flashes when the ZEDI10 Left meters flash and the bottom meter, the right.
Do you get that, or what do you get?
A ZEDI10 mized
Was that supposed to be “Mixer?” We hang on your every word (sometimes in multiple languages), so try to be accurate so we don’t wander off.
Koz
Yes, mixer. I will be careful to eschew obfuscation. 
SO… I decided to make it easier and switch to a mono recording. Here’s what happens now:
I’ve tried a lot of different settings on the ZEDI10. When the levels are in the green, I get a clean recording, but the waveform is really small and the playback is VERY quiet. When I boost the gain, the levels go into the orange and red, which gives me a bigger waveform and louder playback, but the voices distort.
I’m sure others have had this problem. Can you suggest some optimal levels for gains on the ZEDI10, or is this problem solved in post-production. If the latter, how do I boost the volume and get a good clean, distortion-free sound?
Thanks in advance for your help!
I decided to make it easier and switch to a mono recording.
I don’t know that’s a good idea. Some systems when run in mono make it twice as likely to create peak distortion.
Go back to stereo and answer the questions in the above post. What actually happens when you speak or scratch each microphone in each case?
Koz