If you've tried reinstalling the USB drivers for the UX2 on your machine, tested all the available USB ports with it AND tried doing the same on different computers, there's a good chance that the Mic/XLR port and internal hardware components may be the issue.

Have you tested the Mic 2 input jack to see if the audio quality on that port differs? (I'd test that out, if possible).

The GearBox issue... that's ood. One thing you could try is to do a clean install of a new copy of GearBox 3.72 on your computer to see if that helps.

Here's links to GearBox 3.72 Installers:

1. Windows: http://line6.com/software/readeula.html?rid=3121

2. Mac OSX: http://line6.com/software/readeula.html?rid=3120