Kemper Stage issues

Hi
I'm experiencing a noise issue with my current setup. Whenever my hands are on the guitar strings, the sound is perfectly normal. However, when I take my hands off the strings and use the knobs "gain, bass, mid, treble, presence or master" it generates a loud hum and some static crackling/popping. If I turn the knobs while touching "looper" ou "tuner" buttons, the sound is normal. I've already done an isolation test. I disconnected my studio monitors (Edifier), unplugged the USB cables, and plugged the Kemper directly into the wall outlet by itself, using only headphones. In this scenario, the issue completely disappeared! Tweaking the knobs only EQs the normal noise floor of high-gain profiles, with absolutely no crackling.
This points to a ground loop or grounding issue coming from the speakers, my PC, or the room's electrical wiring when everything is connected together, or it can be a hardware issue?
The second issue is physical. My Kemper Stage has an uneven chassis. It is currently sitting on a perfectly flat glass desk, but it doesn't sit flush on all the rubber feet. It gets wobbly when I step on the switches or press the buttons on the edges.
I've read that some units had issues with a bent chassis or uneven rubber feet thickness. Is this considered normal?
I've already tried using other guitars and different cables. I'm not sure if the guitars are properly shielded or not, but the issue persists. The crackling noise only happens when I turn the knobs without my hand resting on the strings. If I touch/mute the strings while turning the knobs, the noise is completely non-existent.Also, since the Kemper came with a slightly uneven chassis, I was worried it might be a damaged internal board

Thanks in advance for the help!