I recently bought my Pod Studio GX and I've been experiencing the terrible ground hum noise. I've troubleshooted this issue extensively and I now know for sure that it's a ground loop issue.When I remove my laptops charger, the sound goes away. While the charger was plugged I tried removing all other USB devices, disabling my Wifi adapter/bluetooth radio/webcam - basically anything I could disable  and the problem still persisted.

So after researching, I thought I'd tried a USB ground loop isolator as a last resort. I bought a Firestone Audio Green Key Isolator and it was just over $80! I've plugged the GX's usb cable into the Isolator and then connected the isolator to my laptop. Now, it's cleaned up the audio a little, and I mean a LITTLE, but the loud hum noise still continues.

I'm going crazy, I've already spent 80 dollars and I can't stand it anymore. Can anyone give me some advice please?

I've attached pictures.