Yes. I had a tuner-only ground loop once.

I noticed the ground loop would go away when I unplugged the antenna wire. Just another possible point for the ground to be better than the rest of the player, hence the loop.

I did a major re-check of all the wiring and found a loose connection. At the same time, I also altered the order that the amps were connected in (two of the variations pictured here). After that, the ground loop went away.

Of course, getting to that point took a long time. I assumed for many weeks that it was the tuner module's fault and went back and forth with the empeg guys trying to see if it was a fault in the module.