I have this list of gear that I am trying to get playing nice together:

  • Windows computer
  • Macbook pro
  • 18i20
  • Presonus 2i2

Currently I am mixing the audio outputs by having my Windows pc connected to my Scarlett 18i20 via USB with the 2i2 connected to the mac with the outputs going to the Scarlett's inputs.

I wish to change this setup so that the Mac is the computer that is connected to the Scarlett however no matter what I try doing to get the PC sound into the mixer there is always a large amount of feedback on the channels coming from the computer.

The only way I can remedy this is to have the PC connected to the Scarlett and have the Mac's inputs routed.

Can anyone give me some idea as to why the Windows PC is so noisy? This is not the first computer I have had with this problem (recently rebuilt the computer, new motherboard, cpu the works)

I have tried connecting the Windows PC in various ways (line output directly to the 18i20 with 3.5m adapter to dual TRS)


If it helps anyone I may create a diagram to show how these computers are connected. It's really driving me insane.

  • Feedback is a sound loop. Have you tried to follow the signal path to and from the pc on every output and input? Jan 20, 2020 at 8:22
  • The PC is connected to the interface by at most two cables (L & R) going to two inputs that are routed onto an output channel through my monitors. I don't know how that could create a sound loop? To me it sounds like there is interference somehow...
    – rattybag
    Jan 21, 2020 at 0:53
  • well I don’t know how you have it routed and you said feedback so is it feedback or interference or is it a ground loop? Jan 21, 2020 at 2:22
  • Right, perhaps feedback was the wrong word. These noises I am describing are more high pitched frequencies that are really obvious when things are turned up. It may be a ground loop issue but it does disappear when I use the exact same setup but have the Mac outputs sent to the audio interface that is connected via USB to the computer, and reappears in the opposite scenario.
    – rattybag
    Jan 21, 2020 at 5:55

2 Answers 2


Have you considered using Dante Via to achieve connectivity between the computers?

  • Hi Mark, I will have a look at this. Thanks for the suggestion.
    – rattybag
    Jan 29, 2020 at 3:44

Windoze needs an external sound card to avoid noise problems.

Look for the feedback loop and then dont do that to avoid feedback problems.

  • I have essentially used an external sound card by using the Presonus 2i2 - unless you mean a PCI one - do you think using a PCI card could fix the issue?
    – rattybag
    Jan 29, 2020 at 3:45

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