Overview

Microsoft's January 2025 security updates, specifically KB5050021 and KB5050009 for Windows 11 versions 23H2 and 24H2, have caused significant disruption for users of USB 1.0 Digital-to-Analog Converters (DACs). Audiophiles, gamers, and professionals relying on pristine audio output from USB DACs are facing device malfunctions with "This device cannot start. (Code 10)" errors, system resource complaints, and unexpected audio volume spikes.

This article explores the root causes, technical background, implications, and potential workarounds users can take while waiting for official fixes.

Background: What Are USB DACs and Why They Matter

A USB DAC is an external hardware component that converts digital audio signals from your computer into analog signals for high-quality audio playback. These devices, popular among audiophiles and professionals, include brands like JDS Labs, FiiO, Denon, and Fosi Audio. USB 1.0 DACs rely on legacy USB audio drivers integrated into Windows, particularly Microsoft's Generic USB Audio driver.

Typically, Windows' generic driver ensures wide compatibility without needing device-specific software. However, this generic approach can sometimes struggle with specialized or legacy hardware, as seen in the current issue.

The Issue Introduced by the January 2025 Updates

Users began reporting that after installing the January 2025 Windows security updates KB5050021 and KB5050009, their USB 1.0 audio DACs failed to start, showing the "Code 10" error, accompanied by the message "Insufficient system resources exist to complete the API." Attempts to reinstall or roll back drivers provide no relief.

In addition to the device startup failures, Windows 11's 24H2 update introduced a separate but related problem affecting USB DACs where audio volume suddenly spikes to 100%, presenting a risk of hearing damage or hardware issues. This "volume spike" bug involves a timing problem in Windows' AudioEndpointBuilder service, which manages synchronization between audio hardware and software.

Technical Details

  • Generic USB Audio Driver Breakage: The updates altered how Microsoft's generic USB audio driver communicates with USB 1.0 DAC devices, leading to compatibility issues and device start failures.
  • AudioEndpointBuilder Timing Bug: A race condition or timing flaw during device wake or reconnection causes Windows to incorrectly set the audio output volume to maximum.
  • Affected Systems: Problems are seen across Windows 10 versions (like Build 19045 with KB5049981) and Windows 11 23H2 and 24H2 builds.
  • Trigger Conditions for Volume Spike: Using USB DACs, especially Creative Sound BlasterX G6, putting the PC into sleep mode, and reconnecting or adjusting volume on the DAC can trigger an unintentional volume max-out.

Implications and Impact

  • For Audiophiles and Professionals: Essential audio devices become unusable or unsafe, potentially disrupting music production, podcasting setups, and high-fidelity listening experiences.
  • Hearing and Hardware Risk: Sudden volume surges to 100% pose risks of hearing damage and equipment malfunction or destruction.
  • Trust in Updates: Frequent updates introducing critical regressions raise concerns about Microsoft's quality assurance processes.

Current Workarounds and Recommendations

Uninstall the Problematic Updates

  • Navigate to Settings > Windows Update > Update history > Uninstall updates.
  • Remove KB5050021 and KB5050009.
  • Reboot the system.

Block Further Updates Temporarily

  • Use Pause updates in Windows Update settings.
  • Use third-party tools like wushowhide.diagcab to hide specific updates.

Use Manufacturer Drivers

  • Some USB DACs offer dedicated drivers that may bypass the disrupted generic driver.
  • Check your hardware manufacturer's website for updated drivers or utilities.

Mitigate the Volume Spike

  • Avoid frequently unplugging and reconnecting USB DACs.
  • Lower system and DAC volume before reconnecting.
  • Disable sleep mode if possible to prevent triggering the bug.
  • Use alternative audio devices (Bluetooth or analog) temporarily if critical.

Await Microsoft Fixes

  • Microsoft has acknowledged these issues publicly and is working on hotfixes.
  • No exact timeline for patch release is available.

Conclusion

The January 2025 Windows updates have exposed weaknesses in Windows’ handling of legacy USB audio hardware, significantly impacting audiophiles and professional users relying on USB 1.0 DACs. With device startup failures and dangerous volume spikes, users should exercise caution, implement workarounds, and monitor official patches.

This situation underscores the challenge of maintaining broad hardware compatibility in complex OS update cycles.

Stay informed and cautious until stable updates restore full functionality and safety for your USB DAC setup.