I am having a very specific problem with a HyperX QuadCast S USB microphone on Windows 11.

Windows detects the microphone correctly at the USB/PnP level and reports that the device is working properly. The microphone endpoint is also created correctly under Windows Audio.

However, Windows cannot actually capture any audio from the QuadCast S.

The input level remains at 0%, the Windows microphone test reports 0%, Windows Sound Recorder reports "No audio input source available", and browser-based microphone tests fail with errors such as:

NotReadableError: Could not start audio source

NotReadableError: Device busy

Could not select device

Microphone access denied / unavailable

The same computer works perfectly with another USB microphone (G55).

The HyperX QuadCast S also works correctly when connected to other computers, so the microphone itself does not appear to be defective.

---

The QuadCast S is not failing at USB enumeration.

Windows sees it as:

HyperX QuadCast S

with:

USB\VID_0951&PID_171D&MI_00\[PII Removed]&0&0000

Windows reports:

Status: OK

Problem: CM_PROB_NONE

ConfigManagerErrorCode: CM_PROB_NONE

ProblemCode: 0

HasProblem: False

GenericDriverInstalled: True

The underlying USB audio device is:

USB Audio Device

Manufacturer:

(Generic USB Audio)

Service:

usbaudio

Driver:

wdma_usb.inf

Driver version:

10.0.26100.8972

The HyperX microphone endpoint is:

Microphone (HyperX QuadCast S)

Instance ID:

SWD\MMDEVAPI\{0.0.1.00000000}.{``[PII Removed]``}

It also reports:

Status: OK

Problem: CM_PROB_NONE

ProblemCode: 0

HasProblem: False

Parent: USB\VID_0951&PID_171D&MI_00\``[PII Removed]``&0&0000

So there are no obvious PnP/device-manager errors.

---

In Windows Settings → System → Sound → Input, the QuadCast S appears normally.

The input volume is set to 100%, but the Windows microphone test reports:

0%

No input is detected.

I also tried enabling "Listen to this device" and selecting the QuadCast itself as the playback device. I still hear absolutely nothing.

I even connected headphones directly to the QuadCast S and could not hear any microphone monitoring.

The microphone's format is shown as:

2 channel, 16 bit, 48000 Hz (DVD Quality)

All available formats in Advanced are 2-channel formats. There is no 1-channel option.

Trying other available formats results in:

"Format not supported by the device"

---

I tested the microphone using several independent browser-based microphone testing websites.

G55

The G55 works normally on all of them.

HyperX QuadCast S

Different sites produce different errors:

mictests.com

NotReadableError: Could not start audio source; Object

webcammictest.com

Device busy

Error code: NotReadableError

mic-test.com

The site does not show an explicit error, but the input level never moves and playback produces no audio.

onlinemictest.com

Microphone not authorized. Please check your media permissions settings.

mictest.to

Microphone access denied

I explicitly granted microphone permission to every site when prompted.

This is also why I don't believe this is simply a browser permission problem.

---

Windows Sound Recorder

I also tested the microphone using the built-in Windows Sound Recorder.

With the G55 selected, recording works normally.

With the QuadCast S selected, Windows reports:

"No audio input source available"

---

I created and tested the microphone under a completely separate local Windows user account:

MicTest

The problem is identical.

The QuadCast S is detected by the OS, but no audio input can be captured.

This appears to rule out a corrupted user profile or per-user audio configuration.

---

Both relevant services are running:

AudioEndpointBuilder → Running / Automatic

Audiosrv → Running / Automatic

I also restarted both services manually using PowerShell:

Restart-Service AudioEndpointBuilder -Force

and:

Restart-Service Audiosrv -Force

After restarting the services, the QuadCast briefly showed an input volume of 0% and the value could not be changed. After reopening the Sound settings page, it returned to 100%, but the microphone still produced no input.

---

I previously disabled Exclusive Mode for the microphone.

No change.

I also tested Windows Audio Enhancements:

Voice Clarity → tested, no improvement

Enhancements → Off, no improvement

The microphone remains completely silent.

---

I completely removed the QuadCast S from Device Manager, including both the speaker and microphone endpoints, then rebooted Windows and reconnected the microphone.

Windows detected and reinstalled the device automatically.

The problem remained exactly the same.

The installed USB audio driver is the Microsoft generic USB Audio driver:

wdma_usb.inf

Driver version:

10.0.26100.8972

The Audio Endpoint driver is:

audioendpoint.inf

Driver version:

10.0.26100.1

There are no Device Manager errors.

---

I completely uninstalled HyperX NGENUITY.

I tested the microphone without NGENUITY installed.

No change.

I subsequently installed the latest version of NGENUITY.

No change.

Therefore the problem does not appear to depend on NGENUITY.

---

I installed the current AMD Chipset Software package for my motherboard/chipset and rebooted Windows.

No change.

---

I tested the QuadCast S on multiple physical USB ports:

USB ports on the computer case

Rear motherboard USB ports

Black USB ports

Blue USB ports

Red USB ports

There is no difference.

The QuadCast is detected in every case, but audio capture remains at 0%.

---

This is one of the most important findings.

I currently have a G55 USB microphone.

The G55 works perfectly on this exact computer.

Windows detects it as:

G55

USB hardware ID:

USB\VID_0D8C&PID_0014&MI_00\``[PII Removed]``&0&0000

Its microphone endpoint is:

Micrófono (G55)

and reports:

Status: OK

Problem: CM_PROB_NONE

ConfigManagerErrorCode: CM_PROB_NONE

ProblemCode: 0

HasProblem: False

The G55 works in:

Windows microphone test

Sound Recorder

Browser microphone tests

Normal audio input applications

Therefore the Windows audio capture subsystem is clearly capable of receiving USB microphone input.

The failure is specifically associated with the QuadCast S.

---

With the QuadCast connected, Windows shows:

HyperX QuadCast S

as a MEDIA device and reports:

OK

With the G55 connected, Windows similarly shows:

G55

as a MEDIA device and reports:

OK

Both use the Windows generic USB audio stack.

The QuadCast therefore appears to enumerate correctly, but something prevents its capture endpoint from actually producing audio samples.

---

For the QuadCast:

Get-CimInstance Win32_SoundDevice |
Where-Object {$_.PNPDeviceID -like "*VID_0951&PID_171D*"} |
Format-List Name,Manufacturer,Status,StatusInfo,PNPDeviceID

returns:

Name         : USB Audio Device
Manufacturer : (Generic USB Audio)
Status       : OK
StatusInfo   : 3
PNPDeviceID  : USB\VID_0951&PID_171D&MI_00\[PII Removed]&0&0000

The PnP device itself reports:

Class                       : MEDIA
FriendlyName                : HyperX QuadCast S
InstanceId                  : USB\VID_0951&PID_171D&MI_00\[PII Removed]&0&0000
Problem                     : CM_PROB_NONE
ConfigManagerErrorCode      : CM_PROB_NONE
Status                      : OK
Description                 : USB Audio Device
Manufacturer                : (Generic USB Audio)
Service                     : usbaudio

The microphone endpoint reports:

FriendlyName : Microphone (HyperX QuadCast S)
Status       : OK
Problem      : CM_PROB_NONE

and:

DEVPKEY_Device_ProblemCode      : 0
DEVPKEY_Device_HasProblem       : False
DEVPKEY_Device_IsPresent        : True
DEVPKEY_Device_IsRebootRequired : False

The endpoint is associated with the correct USB parent:

USB\VID_0951&PID_171D&MI_00\[PII Removed]&0&0000

---

The Windows registry entry for the microphone endpoint exists normally:

HKLM\SYSTEM\CurrentControlSet\Enum\SWD\MMDEVAPI\
{0.0.1.00000000}.{[PII Removed]}

It reports:

DeviceDesc    : Audio Endpoint
Capabilities  : 208
ConfigFlags   : 0
ContainerID   : {[PII Removed]}
HardwareID    : {MMDEVAPI\AudioEndpoints}
CompatibleIDs : {GenericAudioEndpoint, SWD\GenericRaw, SWD\Generic}
ClassGUID     : {C166523C-FE0C-4A94-A586-F1A80CFBBF3E}
Driver        : {c166523c-fe0c-4a94-a586-f1a80cfbbf3e}\0008
Mfg           : Microsoft
FriendlyName  : Microphone (HyperX QuadCast S)

The USB device registry entry is also present:

HKLM\SYSTEM\CurrentControlSet\Enum\USB\
VID_0951&PID_171D&MI_00\
[PII Removed]&0&0000

with:

DeviceDesc          : USB Audio Device
Capabilities        : 160
ConfigFlags         : 0
ContainerID         : {[PII Removed]}
HardwareID          : {USB\VID_0951&PID_171D&REV_0100&MI_00,
                       USB\VID_0951&PID_171D&MI_00}
Service             : usbaudio
Mfg                 : Microsoft
FriendlyName        : HyperX QuadCast S

---

The computer also has several other audio devices installed, including:

AudioQuest DragonFly Cobalt

Elgato HD60 X

AMD High Definition Audio Device

NVIDIA High Definition Audio

Realtek USB Audio

Steam Streaming Microphone

Steam Streaming Speakers

NVIDIA Virtual Audio Device

However, these devices are not preventing the G55 from working.

I also tested the QuadCast while the G55 was disconnected, and the problem remained.

---

The problem is occurring on my current Windows 11 installation, build 26100.

The current USB Audio driver is:

10.0.26100.8972

I have also gone through hardware/software changes during troubleshooting, including replacing/updating relevant hardware and drivers, but the QuadCast S continues to behave the same way on this particular Windows installation.

Importantly, the QuadCast S has been tested on other PCs and works correctly there.

---

So far I have tested or ruled out:

Microphone volume set too low

Windows microphone permissions

Browser microphone permissions

A specific browser

A specific microphone-testing website

A corrupted Windows user profile

Exclusive Mode

Windows Audio Enhancements

HyperX NGENUITY

USB port selection

Case USB ports vs motherboard USB ports

Different USB port types

AMD chipset drivers

Device Manager installation problems

PnP errors

Missing device drivers

Windows Audio service state

Audio Endpoint Builder service

Reinstalling the device

Windows Sound Recorder

Windows Settings microphone test

The G55 works correctly on the same computer, while the QuadCast S works correctly on other computers.

---

At this point, I am trying to determine why Windows can enumerate the QuadCast S and create its microphone endpoint successfully, but cannot open/use the actual capture stream.

The symptoms strongly suggest that the failure is somewhere between the Windows USB Audio driver / WASAPI / audio capture endpoint and the QuadCast's actual capture stream.

The most interesting symptom is that Windows recognizes the microphone, reports no PnP errors, exposes the correct input endpoint, but every application that attempts to open the capture stream either:

reports the device as busy/unavailable,

reports NotReadableError,

reports no input source,

or simply receives zero samples / 0% input.

I would appreciate help identifying what Windows subsystem, registry setting, driver component, or diagnostic tool could be used to determine why the QuadCast's capture endpoint cannot be opened or is returning no audio data, despite the device itself being correctly enumerated.

Is there a Windows Audio/WASAPI diagnostic, ETW trace, Event Viewer log, or other low-level test that can determine whether the QuadCast is:

failing to initialize its capture stream,

being rejected by the Windows USB Audio driver,

exposing an invalid/unsupported audio format,

being opened by another component despite Exclusive Mode being disabled,

or successfully streaming USB audio but having the samples discarded somewhere in the Windows audio stack?

Any guidance on obtaining a more definitive diagnostic would be greatly appreciated.