Leftyjay wrote:Even if the Atomic amp is off? I mostly play through headphones, with the Atomic amp at off.
Yes. It's not about whether the amp is on or off. It's the physical connection to it that makes the Ground loop. The connection via the audio connection cable's screen and the amp's mains safety earth.
The transformers in the isolation box break that direct connection and thus remove the ground loop.
If you mostly use headphones, then try unplugging the audio feed to the amp, or unplugging the amp from the mains outlet. If the unwanted noise is due to a ground loop I will go away when you unplug the amp.