ok I understand your suggestion
again if I Isolate as you suggested would it still be possible
for ground noise to be generated on the band /dj end between their laptop, their mixer, their monitors, etc when plugging into our hdmi and then the noise be broadcast via audio to our system outside of the isolation?
I highly doubt it. The noise is coming from connecting your video input's ground to a mixer input through the laptop. The purpose of the isolation is to keep whatever ground nonsense is happening on the 3rd party side of the stage input separated from the house mixer and PA.
I encounter this ALOT with laptops, even when it's just the laptop and its power adapter plugged in. As a standard practice we connect all laptops through a DI and have zero problems.