The Audio Hijack
macOS is built for seamless hardware integration. When you plug in a new device that has audio capabilities—like a USB-C hub with a headphone jack, a monitor via HDMI, or even a third-party webcam with a built-in microphone—macOS often instantly assumes you want to use this new device. It will automatically change your default audio output or input to the newly connected hardware. This is incredibly frustrating if you have a high-end external DAC or a professional studio microphone set up. Every time you plug your Mac into your monitor, your audio suddenly routes to the monitor’s terrible built-in speakers, forcing you to manually switch it back.
Locking Your Audio Preferences
To maintain your professional setup and stop macOS from automatically changing the default audio device when new hardware is connected, you must rely on a third-party utility, as macOS lacks a native “lock” toggle.
Apple does not provide a built-in setting to prevent automatic audio switching upon connection. If you are constantly battling this issue, the most reliable solution is to download a lightweight, free utility application like AudioSwitcher or Ears. However, to mitigate the issue natively, ensure you explicitly select your preferred device after everything is plugged in. Click the Control Center icon in the top right menu bar, click Sound, and manually select your preferred Output and Input devices. macOS generally remembers the specific hardware configuration (e.g., “When Monitor A and DAC B are plugged in, use DAC B”). By explicitly setting the preference while the offending hardware is connected, macOS is less likely to hijack the signal the next time you plug that specific combination of hardware in.