USB Audio CODEC suddenly has lots of noise -- other numbered CODECs don't?

Hey everybody, I'm dealing with a rough one (for me).

My tracks suddenly have a ton of baked-in noise when recording. Even when the mixer is turned off but I just have the USB plugged in, if I record like that there is still the exact same noise profile. It's a thin ringing frequency at (it seems) 3k Hz, accompanied by consistent noise across the rest of the spectrum. I did soooo much troubleshooting to finally figure it out, but I think I got to the source of the problem: the USB Audio CODEC that the microphone registers as. I finally pared it down to that by using a USB port extender, since the microphone registers each extended USB port under a unique identity, and only the default identity had noise.

SO (under Preferences > Audio Hardware):

Mixer plugged into laptop USB port = "Default Input: Microphone (USB Audio CODEC)"
Mixer plugged into extender port 1, plugged into into laptop USB port = "Default Input: Microphone (1- USB Audio CODEC)"
Mixer plugged into extender port 2, plugged into into laptop USB port = "Default Input: Microphone (2- USB Audio CODEC)"
(etc. etc.)

Only the default "USB Audio CODEC" generates noise. When plugged into any other extension port I get expected sound and normal (minimal) noise.

Anyone have an idea of what I can do to fix this? Do I need to reinstall Audition? Mess around in Device Manager? Eff with my Drivers? Any help would be greatly appreciated! Thank you!