Being a former LG Optimus 2x user i really don't mind waiting the update(i've waited enough for ICS too) because i'm happy with the device as it ...
It may be possible that your phone got flagged as "rooted" when it was checked in the service because of that app you had installed. I suppose the verification software that they have and use checks for certain files that are known to be installed...
It's not an app. As I wrote its something in the system.
I guess with root I can tweak and delete bloatware etc.
The other option is to kill it and get a new one on the insurance and hope for better luck.
I get around 12h batterytime and max 3...
I would the following:
- restart the phone and see if the problem is gone;
- turn off and remove the DAC, then turn on the device, check the audio, turn off again and reattach the DAC and obviously turn on to check if the problem is still there;