jpritz
Thanks for the suggestions. I figured it out.
In case anyone else runs into the same problem: I reloaded the newest driver for the US-2x2, which was just released last week, but it won't run on my system (Windows 10).
First of all, thanks for circling back with helpful info.
I'm using the latest driver with Windows 10 Creators and a US-4x4, which is the same from a driver standpoint. I think there's something else going on with your system, but I'm glad you got it working. The issue may have involved a sample rate change, or possibly a Windows internal sound / ASIO sound conflict...I dunno.
After the next Windows update, consider trying the new driver again (also make sure the firmware is up to date).