Hi,
Welcome to Microsoft Community where you can find all the answers related to Windows.
As per the description provided, it looks like you have issues with AT2020 USB audio when used in Windows 8.
I have these steps which should assist you with this issue.
Method 1: a. Press "win key+ w" and type troubleshooting in the search box.
b. Select troubleshooting from the left side and click on view all, at the left side of the screen.
c. Click and run the recording audio troubleshooter and check.
Method 2:
If this fails to fix the issue, I would suggest you to contact technica for better assistance.
http://www.audio-technica.com/world_map/no_flash/
Hope this information helps. In case you have any questions with Windows, post here at Microsoft Community.