Does the metronome sound clear and loud, as purposely recorded, or is it dim/silent, like hearing a leak or crosstalk? Usually this problem is due to "Stereo Mix" or "What U Hear" settings being abled in the integrated soundcard. How are you recording the guitar? Directly through Digitech or through a miked cabinet?
I'm a little confused about your moving the Digitech further from the computer. In which way do you expect it to help in this case? And this makes me think there's something more that we shoud know about your workflow. How do you monitor? Is the Digitech the only interface selected in Preferences? Every version of SONAR is a separate install. Version 2 is not supposed to uninstall version 1.