The late 2012 iMac update simplified the analog line-in/out and headphone jack. Moving from a MacBook Pro to this iMac, I am now unable to record with my external dynamic mic and small Mackie mixer plugged into the headphone jack with an RCA to 1/8" cable. In the Sound preferences, the line-in does not show up as an input option, only the internal mic.

The most popular solution I've found is the obvious one, namely, get a USB audio interface. But I do so little recording that it seems silly to buy another piece of gear to functionally do much of the same as my mixer does already, and I am not interested in doing so.

Is there another solution to this problem? A mono cable (which is fine for voice recording) or a TRRS cable that makes my iMac think a compatible mic/headset has been connected? Clever and outside-the-box ideas are welcome.

  • A USB audio interface does not do the same thing as your mixer at all. The point of an audio interface is to have a properly isolated analog to digital converter that can record noise free (or at least significantly lowered) and impedance matched audio. It shares almost no functionality with what your mixer provides at all, particularly no more so than your line input provides. You would absolutely get significantly better results if you got a decent USB audio interface.
    – AJ Henderson
    Commented Aug 8, 2013 at 1:03
  • In my mind, they both would provide XLR mic inputs, supply phantom power if needed, control mic gain, and allow headphone monitoring of the channel. That seems pretty similar. The main difference being an A/D converter isolated from the computer and perhaps monitoring the full computer mix, neither of which are significant for my specific needs. For many others, these are important, even critical, just not for me in this case.
    – John Rygielski
    Commented Aug 8, 2013 at 1:39
  • Gain is also controlled by the line input and headphone monitoring can be done from the line input as well. It does provide phantom power and an XLR input, but keeping the input balanced all the way to the ADC is a significant advantage that distinguishes it. The point of a mixer is to combine multiple signals in to one signal. Using it to convert a balanced signal to an unbalanced one prematurely is not a benefit to your process, but a detraction.
    – AJ Henderson
    Commented Aug 8, 2013 at 13:29

3 Answers 3


The Late 2012 27" iMac does not appear to have line-in, just a headphone port. I'm not sure which model you have, but if the 27" doesn't have it, I doubt the smaller ones will.

You can double-check by selecting About This Mac from the Apple menu. Then click the More Info button and then the System Report... button. Next, click on Audio to the left. If you don't have an entry for Built-in Input then you probably don't have line-in in your mac.

enter image description here

If you don't have audio input hardware, then you will need to add some kind of audio interface.


Apple's iMacs use a 4-pin TRRS headphone port which combine analog audio output and input and need a connector like this:

enter image description here

(© wikipedia, user Imaadwhd)

Just take an adapter like this and plug in your standard headphones and mic.


My Late 2012 iMac (iMac13,2) says in Apple System Information (under Audio, but not under "Devices") that it has an "Intel High Definition Audio", which contains External Microphone / iPhone Headset with "Connection: Combination Output".

The adapter that speakr references (with a 4-pin TRRS headphone jack) should work to transform other audio plugs into the line-in format Apple expects.

Screen shot from Apple System Information

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