Ground noise in Roland GI-20

[blissMan77]

I've started using a Roland GI-20 midi controller connected to a PC via USB. I use a Roland GK2h 13-pin pickup mounted to an older strat (heavy, no trem). I record midi using Cubase VST triggering VST Intstruments. All is well, except for a terrible ground hum when I connect the GI-20's guitar out (standard 1/4" audio out) to either a live amp or my PA. My short-term solution has been to not use that jack, but rather to connect the guitar's standard 1/4" input directly to the amp or PA mixer, i.e. bypass the GI-20's standard instrument path altogether. I have tried ground-lifting all but the computer, to no avail. (the monitor is an LCD, by the way). I've tried separating the guitar amp's AC outlet and putting everything else on one circuit - no luck.

Next I'll try connecting all power cords to just one AC outlet.
Can anyone think of anything else?
Thanks,
STeve

[JoeNovice]

I'm late in my reply to this topic but....

I've started to use this and have found the same problem. Have you any better solution after all this time?