I would like to know how to force a Mac to recheck the USB connections without needing to physically unplug and plug them again. Is there a Terminal command for this?

Context: I have a USB audio connection (an amplifier with a DAC) directly connected to my Mac (description below). With everything on, once I plug the USB to the Mac the audio output is correctly detected and it appears in the menu bar under the sound icon. Also, as expected, when I power off the amplifier the USB audio output is no longer available (it disappears from the sound menu).

The problem appears when I power on the amplifier again, since my Mac does not recognize the USB sound output. To make it work, I need to physically unplug and plug again the USB with the amplifier turned on.

Thus, if there was some system command (either through Terminal or by other means) to force the Mac to recheck the USB connections that would be time saving for me.

Configuration: The issue occurs on two Macs, both of them with Big Sur 11.4. One is a Mac Pro 2013 and the other a Macbook Pro 2018 13". I also had the same problem with Catalina. The DAC/Amplifier is an Emotiva TA 100. For either mac, I use a single cable directly connected between the computer and the amplifier.

Update (16/October/2021): I "solved" my problem by buying another DAC. I understand that my previous one had some problem, but it would be nice to have a software way to circumvent the issue.

  • Is the DAC connected directly to a USB port on both Macs, or through a hub of some sort?
    – IconDaemon
    Jul 5, 2021 at 0:31
  • @IconDaemon, it is connected directly to the mac, no hub or other connections.
    – Davi
    Jul 5, 2021 at 1:52
  • I just found this similar question apple.stackexchange.com/questions/271252/… . However, the provided answer is not a valid one, since it only applies to smart USB hubs; which is not my case.
    – Davi
    Jul 10, 2021 at 22:06
  • Can you see the device in the app Audio MIDI Setup? It's in /Applications/Utilities.
    – IconDaemon
    Jul 10, 2021 at 22:38
  • Yes, when the dac is recognized, I can see it in Audio MIDI setup.
    – Davi
    Jul 11, 2021 at 17:07

1 Answer 1


You could try launching System Information and looking at the USB section. Connected devices show up there and CMD-R refreshes the information. That might cause the Mac to again recognize the amplifier.

  • I tried now, but it didn't helped. The DAC/Amplifier (Emotiva TA 100) didn't show up when I entered the system information. After unplugging and plugging it again, it was recognized in the Sound menu bar icon. And after leaving and returning to system information, it appeared in the system information.
    – Davi
    Jul 5, 2021 at 15:04
  • 1
    This answer won't work. Cmd-R only refreshes the display - it doesn't in any way cause the Mac to actually do something with the USB ports, such as "recognizing" or "go looking for" new devices or anything like that.
    – jksoegaard
    Jul 5, 2021 at 18:04

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