Does the DX80 supports any USB microphones? I have a customer who wants connect an external microphone to a DX80 because he wants to be able to mute the mic without having to sit within arms reach of the integrated mute button. I don't think the TRC6 remote is compatible with the DX80 for muting either.
There isn't any specificly supported microphone. If the microphone supportes the HID protocol, then it should work. See this document https://collaborationhelp.cisco.com/article/en-us/nkiifbo - while it refers to USB headsets, the same should apply for a microphone.
If you end user is getting too far away from the device, then that may defeat the purpose of using a desktop based unit, and perhaps a different model endpoint would be a better choice?
Is it compatible with the Cisco table microphone?