macOS Monterey audio dropouts when USB‑C audio interface runs >48 kHz through Thunderbolt dock

Environment

MacBook Pro (Intel) running macOS Monterey 12.6.2; Focusrite 2i4 USB‑C audio interface connected to a CalDigit Thunderbolt 4 dock; Logic Pro and Zoom both used; sample rates tested: 44.1kHz, 48kHz (OK), 96kHz (dropouts)

Symptoms

At session sample rates above 48kHz (96kHz), periodic crackling and dropouts occur in DAW playback and while recording; CPU and I/O appear moderate; dropping to 48kHz resolves the glitches; dropouts coincide with USB device reconnects in system log

Observations

Console.app shows repeated IORegistry messages: 'AppleUSBHostPort::deviceDisconnected' and 'kUSBHostEvent_DeviceDisconnected' around the time of glitches; system.log shows 'IOUSBHostHIDDevice' reconnects; Audio MIDI Setup shows the interface periodically visible then missing for <1s; switching the interface directly to MacBook USB‑C bypassing dock eliminates the dropouts even at 96kHz

Already attempted

Updated macOS to latest 12.6.2 build and Focusrite firmware — issue persists; tried different Thunderbolt cable and dock firmware update — still see intermittent disconnects; created aggregate device at 48kHz and 96kHz — only 96kHz via dock shows instability; ran Apple Diagnostics — no hardware faults reported

Question

Why do audio dropouts and brief USB disconnects occur only at sample rates >48kHz when the interface is connected through the Thunderbolt dock, and how to work around or fix the host/dock interaction without losing multi‑channel high‑sample‑rate capability?

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AI DIAGNOSTICS

Incident analysis

Updated 1w ago• Trouble ID

Most likely causes

Thunderbolt dock USB controller firmware bug failing under high isochronous bandwidth at >48kHz 90%

MacOS USB host stack interaction with dock bridge driver causing periodic resets at heavy isochronous load 60%

Focusrite firmware interacting poorly with hub/bridge when sample rate >48kHz 30%

Summary

Evidence points to intermittent USB link resets between dock and Mac when device bandwidth or isochronous USB scheduling increases at higher sample rates. The dock's controller firmware, hub bandwidth allocation, or Thunderbolt-to-USB bridge may not reliably handle the sustained isochronous load at 96kHz leading to brief disconnects. Direct connection bypassing the dock removes the failing bridge, confirming the dock as a likely culprit.

Suggested Fixes

Diagnostic step 1

For immediate stability, connect the audio interface directly to the MacBook's USB‑C/Thunderbolt port when using >48kHz sample rates.

Diagnostic step 2

Collect IO logs: run log stream during a reproduction (log stream --predicate 'process == "kernel"' --info) to capture disconnect messages and attach to vendor support case.

Diagnostic step 3

Try toggling 'Prevent computer from sleeping' and disable other high-bandwidth devices on the same dock; test with a known-good Thunderbolt cable and different dock if available.