Fix NS_E_TOO_MANY_AUDIO (0XC00D1B5C) instantly

This error is a pain, I know

You're trying to record or make a call, and Windows throws up NS_E_TOO_MANY_AUDIO (0XC00D1B5C) with the message "It is not possible to specify more than one audio input." It usually happens when you plug in a USB microphone on top of your built-in mic, or when a second webcam with a mic gets detected. The fix is simple — you need to tell Windows which mic to use by disabling the extra one.

Step-by-step fix

1. Right-click the speaker icon in your system tray (near the clock) and select Sounds.
2. Go to the Recording tab. You'll see a list of devices — your active mic has a green checkmark.
3. Right-click any device you don't want to use (like your built-in Realtek microphone if you're using a USB mic) and choose Disable.
4. Now right-click the one you do want and choose Set as Default Device. Then click OK.

That's it. The error should vanish immediately. If you're in the middle of a recording or call, restart the app (like Zoom or OBS).

Why this works

Windows apps often try to grab the first available audio input they see. When there are two mics — say, your laptop's built-in array and a USB headset — they both appear as valid inputs. But some apps (especially older ones or those using Media Foundation) only expect one. The error code 0XC00D1B5C specifically comes from NS_E_TOO_MANY_AUDIO inside the Windows Media SDK. It's not a hardware failure — it's a software limitation. By disabling the extra device, you're forcing the app to pick the one you want without confusion.

When this fix doesn't work

Rarely, the issue is with a single device that's sending multiple input streams. For example, some USB microphones with built-in monitoring show up as two separate inputs. If you only have one mic but see two entries in the Recording tab (like "Microphone (USB Audio Device)" and "Headset Earphone (USB Audio Device)"), disable the one you're not using. Also, check if your audio drivers are up to date — outdated Realtek or Conexant drivers can cause duplicates. Update them from your motherboard or laptop manufacturer's site, not from Windows Update.

Less common variations

Some users hit this error even after disabling extras. If that's you, try this:

• Open Device Manager (right-click Start), expand Audio inputs and outputs, right-click the unused mic, and select Disable device. This is a more aggressive disable and sometimes catches what Sound settings miss.
• If you're using a DAW or audio software like Audacity, check its audio settings — some apps have a dropdown to select the input device. Make sure only one is enabled there.
• For pro audio interfaces (Focusrite, Behringer), unplug and replug the USB cable. This resets the device enumeration and can collapse duplicate streams into one.

Prevention for the future

To avoid this error reoccurring, commit to using one mic at a time for each app. If you switch between a headset and a standalone mic, don't keep both plugged in. Disable the built-in mic permanently if you never use it — right-click it in the Recording tab and choose Disable. This stops Windows from detecting it as an option later. Also, check your app's settings: Skype, Discord, and Zoom all let you pick a specific input device. Set it to your preferred mic, not "Default Device." That bypasses the error entirely because the app skips the enumeration step.

If you're still stuck after all this, try running the Windows Audio Troubleshooter (search "Find and fix problems with playing sound"). It's basic but sometimes catches registry glitches. And remember — this error is almost never a hardware fault. It's Windows being too helpful with multiple inputs. You just need to pick one.