How to use 2 Mics on Adobe Audition on Windows

Tell you what - I'll do the whole answer...

The OP never mentioned what mics he was using, and the situations with 'normal' mics and USB mics are a little different. With normal mics, you're going to need some means of feeding them into the same input, but separated - which you can do with a single stereo input, obviously, although using a small mixer is a much better solution, because it gives you monitoring and panning options, etc

With USB mics, it's different. Yes, you need to be able to aggregate them, and they all need their sample rates to be synchronised. To my knowledge there is only one piece of Windows software out there that is supposedly capable of doing this with more than one USB source, and that is called ASIO4ALL. Fortunately for you, it's free. It actually acts as an interface between your inputs and whatever software you're using it with. It's ASIO-based, and that means that it works very nicely with Audition, because that's ASIO-based too. You can find it here and it's well worth reading through the introduction and use guide.

What you have to do with it when you download it is run the installer, and when you open Audition, you go to Edit>Preferences>Audio Hardware and select ASIO in the Device Class section. Then, when you click on Device, you should find ASIO4ALL listed, and when you click on Settings, it should take you to the ASIO4ALL app, where you can set it up. What it does, essentially, is to use one USB mic as a sync source, and use that (with a bit of trickery) to synchronise the other. You should then be able to record them on separate tracks, but simultaneously. At least that's the theory - I only have one USB mic available here so I've never tried it in practice. But hey, ASIO4ALL says it's possible...