Line6 has not been to any help for me even though I found a good workaround for this issue they were not interested in compensate something for this to let others have a working workaround. I have now been using the UX2 with 10.8.2 mountain lion for about 3 month even though line6 have not been solving this issue for 6-7 month. There is christmas now and I think it would be fair to share my findings if it could be to any help for others having the same issuses that I had.
Ok first of all you need to install the latest drivers from Line6 (7.1.7), you will still have these issues after installing these drivers. Might work one out of 10 or so. If you have the UX2 when popping and cracking sound is back you should do the following.
1. Press and turn on the 48v phantom power so that the red lap is on
2. Turn off the 48v phantom power again (the new drivers and 10.8.2 with Apple has changed some power outage for the usb port and Ux2 seems to have a condensator that needs to be 100% empty of power)
3. Now you should remove the USB cable, (Important don't remove the USB cable from the computer!!!!!, remove the USB cable from back of the UX2 device very important that you do this!)
4. Wait about 10 sek with the usb cable removed
5. Plug in the USB cable in the back of the UX2 device again.
6. Workaround is ready and the popping and cracking sound should be gone!
Now you can aldo turn on the 48v phantom power if needed, repeat this procedure if you have the strange sounds again after hibernation of your laptop etc.
Happy Christmas all of you and I hope you can do some recordings again without the irritating sound. It might work to only follow and repeat step 3-6 abow also. The reason most of the people have not found this workaround is that 90% of all users are removing the cable from the laptop probably including the Line6 support then....
This is verified with Garageband but probably this solution works for Logic and other programs too.
There is still an issue with the Line6 drivers while there is not possible to use Mic and Instrument at the same time even though there is a setting for this within the drivers and operating system settings for Line6.
I was about buing a new guitar from Line6 the new Variax JTV model but I have changed my mind while I can't take the risk to have to wait for driver updates and fixes while I assume there is similar issues with all the gear. I think I will look at the fender by roland guitar instead, more limited in its software but the product seems to be verified and working out of the box without any built-in features.
Happy Christmas and a good new year!!