Current Events > HELP my monitors are humming, 2 laptop/2 interface setup

(+) Yeah! (+)

Hello- I currently have a setup for livestreaming music. I'm only getting into this hardware side of things recently so I'm looking for general guidance as well for how I can make this better. I've attached a rudimentary diagram to help illustrate my issue https://imgur.com/a/nCyrviV

(Laptop 1) Mac+Apollo Twin X goes to two monitors, with a line out INTO a Scarlett 2i2, which is in turn connected to a PC (Laptop 2)

The Mac & Apollo are plugged into the same power strip. The monitors are plugged into a separate power strip. However, no matter where I plug the PC into, there is a humming coming out of the monitors!

The humming stops whenever the PC is unplugged, or whenever I remove the line connection between the Apollo & Scarlett. Obviously I need both those connected for my stream to work- anyone know what exactly is happening?

Here's some additional info about my setup and ideas about what could be going wrong. Any suggestions here would be awesome as well!

• I am streaming this way because my Mac isn't powerful enough to run OBS and Ableton simultaneously, so I make music on my Mac and stream it from my PC via capture card. I have two audio interfaces because I use the Apollo for the music making output into the Scarlett which also is attached to a room mic. I'm sure all this could be solved once I can invest in a single computer that can do both tasks with a single interface
• I had no issues when I had this setup at a shared studio when the monitors and Apollo were plugged into a power conditioner, and the PC & Mac were plugged into separate outlets. Might the solution be a power conditioner? If so, what is a budget option? They had a Furman which seemed to work nicely.
• I am using a TS cable to go mono out from the Apollo into Input 2 of the 2i2. Maybe if I used a balanced cable the issue could be solved?

Thanks for the help! Sorry for the ruddy drawing