What would sound best here? (new PC monitor, 3.5mm out)

[Scam]

I'm currently using my work MBP and personal desktop PC via the same monitor/keyboard/mouse via a hdmi+usb switcher. Both machines have 3.5mm jacks out, going via a splitter into my Creative 2.1 amp/speakers. Unfortunately the MBP has taken to buzzing and I'm not sure why… probably the splitter but it's hard to diagnose as you need a Mac dongle regardless

My question is.. I've just bought the lovely AOC 24G2U monitor. If rather than using 3.5mm out on both machines, I instead take the audio via HDMI (or Displayport) into the monitor, and use it's 3.5mm headphone jack to my amp/speakers… will I notice any degradation in quality?

NB: I only have onboard sound on my PC, and obviously same for the MBP. I just want music to sound ok still.

 

[Scam]

It's the 3.5mm out in the MBP, not sure if that's a line out or simply a headphone jack?

But i wouldn't be surprised either if the splitter is the cause.

It's not the 3.5mm splitter, I've tried taking that out of the equation. It's actually the hdmi switcher so I'm trying to see if I can get around it without having to buy another! The new monitor also has multiple hdmi inputs so I could try going hdmi directly from each machine and only using the switcher to switch usb. Confusing I know..

For what it's worth only the Mac makes a buzzing noise through the speakers when everything is plugged in, my PC is fine. I actually think it's the Mac dongle as it reduces massively if I remove the hdmi or usb from the dongle. And obviously stops completely if I remove the dongle. (Dongle being the usb-c to AV multiport adapter required for a MacBook Pro)