I have been looking at how to connect multiple Mics to my Mac. So far I have followed tutorials on YouTube which guide me towards creating an aggregated device on the Audio MIDI utility. I do this and have the set up as follows:

Audio Settings Pane

I have found that when I open GarageBand I get all the channels I would expect but non of the mics seem to be picking up sound.

Oddly, when I use two mics this seems to work perfectly fine and I am able to record on GarageBand with 2 inputs easily.

Does anyone know if I am doing something wrong or if the Mac is just unable to power three mic inputs?

1 Answer 1


You need a proper audio mixer.

Does anyone know if I am doing something wrong or if the Mac is just unable to power three mic inputs?

You aren’t doing anything wrong; it’s a limitation of the system. Every time you plug in a new device, macOS wants to make it the new default. I’ve never been able to get more than two devices recognized and functioning simultaneously.

However, if you use a proper audio mixer, it becomes a single device with multiple channels (I’ve configured mixers with up to 16 channels). If you’re concerned that the USB microphones are digital versus the analog microphones/instruments plugging into the mixer, I can assure you that the DAC used in the mixer is of much higher quality than the USB microphones.

  • I wonder whether this limitation could be bypassed with Audio Hijack/Loopback etc. OP has already invested in 3 USB mics, so to switch to external hardware would need new mics too. It's not something I've ever investigated as I have enough 'proper' mics to not be looking at USB, but it might just be worth a shot [I think both have free demo periods].
    – Tetsujin
    Commented Jan 22, 2023 at 16:32
  • I don’t think Audio Hijack access the raw devices, though I could be wrong. It’s documentation says it works with mixers (which makes sense) but nowhere does it show multiple microphones. It won’t hurt to try, but I don’t have multiple USB microphones to test with.
    – Allan
    Commented Jan 22, 2023 at 17:16
  • Yeah, I'm also purely theoretical on this. I just have nothing to test the theory with. I don't own a single 'USB audio device' that isn't already a full interface.
    – Tetsujin
    Commented Jan 22, 2023 at 17:17

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