XDJ-XZ feedback "hum" on outputs and within OBS

Hi all, 

Two part question here related to the same issue.

• I've noticed audio feedback coming from the outputs on my XDJ-XZ-W that sounds like a "hum". I was able to isolate the source as the power cable, as when I plug the power cable in, the hum is being picked up even if the controller is off. Is there a way to prevent this? I know it may have something to do with the grounding, but I've tried using a wire to ground the controller using the screw on the back to no avail.
• In addition, from my computer, I route the signal to OBS (see attached screenshots) where I noticed a SUPER weird phenomone. Photo 1 shows OBS in full screen, where the signal is a mild hum and coming in around -57 or -58 dB. However, when I change the screen size (photo 2), the hum becomes a loud stutter and shows at -55 dB. This I find bewildering and was curious if anyone encountered this before/knows a fix.
  
  Photo 1 : OBS in full screen , hum at a reasonable -57/-58dB

Photo 2: OBS in windowed screen, loud stuttering hum at -55db