Hi, Tony,

I was away for a day, thanks for your reply!

The empeg is known to be good. It worked with a different amp that I gave to my girlfriend. I just removed the old amp, plugged in the new one and - nothing! Only after playing with things I discovered the "reversing" trick. It didn't make any sense to me, but hey, it worked!

I won't have time for serious troubleshooting until later. It works for now. The ground-loop-noise is barely noticable as long as I leave the gain on the amp turned down.

Armin