Try being just a little bit humble!!! We might be more receptive.
You are asking us to do you a BIG favor and help you solve a technical problem that you have been unable to solve yourself. We don't owe you a solution. This isn't one of those forums where everyone tries to see who can be the biggest asshole. We generally treat each other with a little respect, and we ask you to do the same. We understand you are frustrated because you spent a lot of money on new toys and the don't work right. Most of us have been there, but that's no reason to yell at us.
I read your post, and I do not want to download a external zip file from someone I don't know (computer safety). What I see in front of me now is kind of like saying "My car won't start" and sending us a stock photo of your car, and saying "the dealer said it's OK", and expecting me to magically realize you have a bad ballast resister. I don't know what you may have had in your previous edits of your post, but what I have for information now isn't particularly helpful. But realistically, even if we have the wave file and images, that typically doesn't help figure out what the problem is.
End of lecture. Now back to your problem. This is all troubleshooting 101...
- replace battery in preamp for good measure, this has driven people crazy before... you wouldn't be the first. Just do it.
- find a way to reproduce the problem on a consistent basis
- Do not assume the mics are good because MM said they were good. Maybe they just couldn't reproduce the problem.
- swap L/R inputs into Korg. Does the problem move to Right? If so, then it's in the mics/pre/cables. If not, it's in the Korg.
- What happens if you plug in ONLY the left channel, then ONLY the right channel. Does that matter?
- Try it without the preamp and run mic in. Does it go away? If so, it sounds like maybe it's the preamp.
- Find a local friend with mics and recorder so you can try your mics in his recorder, and vice versa...
- We don't know if you have turned on the plug in power in addition to the preamp. It's a legitimate question.
- Using a decent voltmeter, measure the DC voltage coming out of the preamp (into the Korg) across the tip/sleeve. Basically, there shouldn't be any... there should be a small random AC voltage at times when there is sound input, but not DC. If there is, then perhaps your preamp is leaking DC back towards the recorder. It's not supposed to do that, but it's happened before.
- This is just a matter of an organized process of elimination.
Good luck.