My modded guitar amp makes popping sounds under some circumstances

I have a Fender Mustang GT-40 guitar amp and I decided to try to mod it. I’m very new to this, so I’m learning a lot. For the mod, I connected the speaker output pins to a voltage divider circuit to bring the speaker level signal down to line level so I can go straight from the amp to FOH or an audio interface. I connected the line output to a 1/4” jack, and connected it to my audio interface (presonus studio 2/4C) and turned it on and it worked fine. The max signal I was reading on my audio interface was -12db, barely in the yellow. Then, I tried again with the exact same setup except this time my laptop was connected to my external monitor via hdmi. Now my audio interface was only getting a repetitive popping sound from my amp (maybe 5-8 times per second). When I unplugged my hdmi, it was back to normal. If I only unplugged the hdmi from the monitor (still plugged into laptop) then the popping stopped, but then if I touch the end of the hdmi cable to the metal frame of the monitor, it comes back again. Does anyone have an idea of what might be going on, or if this is a huge problem with my mod and I shouldn’t plug it into a sound board in this state? It works perfectly except for the weird hdmi thing. Here’s the circuit: