Does iMac Retina 5K, 27-inch, 2020 sound card support playback audio at 192khz? In my case, I see that this type and model can support only 96khz playback audio. Thanks.

You seem to already have answered your own question, even supplied a link to an Apple support document that appears to confirm it.

If you need to work with audio at the higher sample rate, you will likely need to find a USB DAC and software that is compatible with your hardware and the macOS version you are running.

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