Audio interface output - the correct way?

Hello all,

I have a question on the correct way to connect the outputs of the audio interface to the main mixer board. Let’s say that I have a USB audio interface with Main output L & R or 1 & 2 (such as RME Babyface or Universal Audio Apollo). At home in the studio, I would connect Left (or 1) to the left monitor, and Right (or 2) to the right monitor. Great! Now with live gig, how should I connect the outputs to the main mixer board?

  1. Should I run 2 cables from the audio interface to the main mixer board; i.e. outputs L & R to input channels 1 & 2?
  2. Similar to above, should I run 2 cables from the audio interface to the main mixer board; i.e. outputs L & R to input channels 1 & 2 and pan the main mixer board inputs 1 & 2 to 100% Left and 100% Right to keep the stereo image?
  3. Should I just connect one of the outputs, i.e. Left from the audio interface to 1 of the inputs on the main mixer?
  4. Or can I use a Y-cable to combine audio interface outputs L & R into 1 single channel on the main mixer?

Thank you all!


to start with 4) no good option as you shortcut the outs of your soundcard. To add signals 2 resistors of say 10kOhms would be necessary for mixing signals at minimum.

Here Option 3) would be the right way but only if your mixer is short of inputs. You’ll have to keep an eye on the channel panpots in cantabile to summarise left and right signals of stereo plugins on one channel!

  1. I prosume here is meant to keep the panpots of the main mixer in middle position? What you get is a mono signal on FOH (probably not the worst decision as you’ll see later).

  2. Here the complete stereo panorama is kept. Seems to be great at first glance but can make lots of trouble. If you use stacked sounds which are largely spread in panorama f.e. this can lead to the situation that audience standing near left speaker array will hear a totally differnt sound than those standing near the right array and audience standing in the middle or far away again will hear something different.

I personally would chose option 5): Use sceario 2) but let the FOH man decide how far he wants to spread your keyboardsound (probably also depending on the place you play). Doing this you normally find a proper compromise.

My 2 cent, regards, humphrey

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Hi humphrey,

Thank you very much for your detailed explanation. I think I’ll go with either option #3 (just 1 mono channel) or #5, depends on the situation.