我有一个 M-track 8 音频设备（8 个 I/O）。播放效果很好。然而，麦克风（48 伏 XLR 麦克风）几乎没有发出任何声音。录音时，任何应用程序的音量上限均为 15%。
- 根据混频器频谱分析仪，它们工作得很好。
- 如果我将 m 轨输入重定向到模拟输出并使用内置麦克风进行录制，则它可以正常工作
- 如果我在 macOS 或 Windows 中录制，它可以正常工作。
所以问题出在 ALSA 或驱动程序的某个地方。这是一个普通的 USB 音频类设备，因此驱动程序不太可能是问题（在 Gentoo、Ubuntu 20.04 和 Ubuntu 18.04 live-usb 中重现）。
alsamixer显示所有输入均为 100%pavucontrol以 100% 显示所有输入- 我尝试添加一些
.asoundrc配置来强制 96kHz，但没有任何作用 - 该问题与麦克风增强无关。信号超弱
混合器-c2：
Simple mixer control 'Mic',0
Capabilities: cvolume cswitch
Capture channels: Front Left - Front Right - Rear Left - Rear Right - Front Center - Woofer - Side Left - Side Right
Limits: Capture 0 - 127
Front Left: Capture 127 [100%] [0.00dB] [on]
Front Right: Capture 127 [100%] [0.00dB] [on]
Rear Left: Capture 127 [100%] [0.00dB] [on]
Rear Right: Capture 127 [100%] [0.00dB] [on]
Front Center: Capture 127 [100%] [0.00dB] [on]
Woofer: Capture 127 [100%] [0.00dB] [on]
Side Left: Capture 127 [100%] [0.00dB] [on]
Side Right: Capture 127 [100%] [0.00dB] [on]
Simple mixer control 'Mic',1
Capabilities: cvolume cvolume-joined cswitch cswitch-joined
Capture channels: Mono
Limits: Capture 0 - 127
Mono: Capture 127 [100%] [0.00dB] [on]
Simple mixer control 'M-Audio M-Track Eight',0
Capabilities: pvolume pswitch
Playback channels: Front Left - Front Right - Rear Left - Rear Right - Front Center - Woofer - Side Left - Side Right
Limits: Playback 0 - 127
Mono:
Front Left: Playback 121 [95%] [-6.00dB] [on]
Front Right: Playback 121 [95%] [-6.00dB] [on]
Rear Left: Playback 127 [100%] [0.00dB] [on]
Rear Right: Playback 127 [100%] [0.00dB] [on]
Front Center: Playback 127 [100%] [0.00dB] [on]
Woofer: Playback 127 [100%] [0.00dB] [on]
Side Left: Playback 127 [100%] [0.00dB] [on]
Side Right: Playback 127 [100%] [0.00dB] [on]
Simple mixer control 'M-Audio M-Track Eight',1
Capabilities: pvolume pvolume-joined pswitch pswitch-joined
Playback channels: Mono
Limits: Playback 0 - 127
Mono: Playback 127 [100%] [0.00dB] [on]
lsusb -vv -d 0763:4003
Bus 001 Device 049: ID 0763:4003 M-Audio
Couldn't open device, some information will be missing
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 64
idVendor 0x0763 M-Audio
idProduct 0x4003
bcdDevice 1.05
iManufacturer 1
iProduct 3
iSerial 0
bNumConfigurations 2
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0148
bNumInterfaces 4
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 500mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 3
bFunctionClass 1 Audio
bFunctionSubClass 0
bFunctionProtocol 32
iFunction 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 32
iInterface 3
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 2.00
bCategory 8
wTotalLength 0x00a7
bmControls 0x00
AudioControl Interface Descriptor:
bLength 8
bDescriptorType 36
bDescriptorSubtype 10 (CLOCK_SOURCE)
bClockID 41
bmAttributes 3 Internal programmable clock
bmControls 0x07
Clock Frequency Control (read/write)
Clock Validity Control (read-only)
bAssocTerminal 0
iClockSource 9
AudioControl Interface Descriptor:
bLength 8
bDescriptorType 36
bDescriptorSubtype 11 (CLOCK_SELECTOR)
bClockID 40
bNrInPins 1
baCSourceID(0) 41
bmControls 0x03
Clock Selector Control (read/write)
iClockSelector 8
AudioControl Interface Descriptor:
bLength 17
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 2
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bCSourceID 40
bNrChannels 8
bmChannelConfig 0x00000000
iChannelNames 19
bmControls 0x0000
iTerminal 6
AudioControl Interface Descriptor:
bLength 42
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 10
bSourceID 2
bmaControls(0) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(1) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(2) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(3) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(4) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(5) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(6) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(7) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(8) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
iFeature 0
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 20
wTerminalType 0x0301 Speaker
bAssocTerminal 0
bSourceID 10
bCSourceID 40
bmControls 0x0000
iTerminal 0
AudioControl Interface Descriptor:
bLength 17
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Microphone
bAssocTerminal 0
bCSourceID 40
bNrChannels 8
bmChannelConfig 0x00000000
iChannelNames 19
bmControls 0x0000
iTerminal 0
AudioControl Interface Descriptor:
bLength 42
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 11
bSourceID 1
bmaControls(0) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(1) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(2) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(3) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(4) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(5) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(6) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(7) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(8) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
iFeature 0
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 22
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 11
bCSourceID 40
bmControls 0x0000
iTerminal 7
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 4
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 2
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 4
AudioStreaming Interface Descriptor:
bLength 16
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bmControls 0x00
bFormatType 1
bmFormats 0x00000001
PCM
bNrChannels 8
bmChannelConfig 0x00000000
iChannelNames 11
AudioStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bSubslotSize 4
bBitResolution 24
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x01 EP 1 OUT
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 1
AudioStreaming Endpoint Descriptor:
bLength 8
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x00
bmControls 0x00
bLockDelayUnits 2 Decoded PCM samples
wLockDelay 0x0008
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 17
Transfer Type Isochronous
Synch Type None
Usage Type Feedback
wMaxPacketSize 0x0004 1x 4 bytes
bInterval 4
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 5
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 5
AudioStreaming Interface Descriptor:
bLength 16
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 22
bmControls 0x00
bFormatType 1
bmFormats 0x00000001
PCM
bNrChannels 8
bmChannelConfig 0x00000000
iChannelNames 19
AudioStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bSubslotSize 4
bBitResolution 24
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 1
AudioStreaming Endpoint Descriptor:
bLength 8
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x00
bmControls 0x00
bLockDelayUnits 2 Decoded PCM samples
wLockDelay 0x0008
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 254 Application Specific Interface
bInterfaceSubClass 1 Device Firmware Update
bInterfaceProtocol 1
iInterface 10
Device Firmware Upgrade Interface Descriptor:
bLength 9
bDescriptorType 33
bmAttributes 7
Will Not Detach
Manifestation Tolerant
Upload Supported
Download Supported
wDetachTimeout 250 milliseconds
wTransferSize 64 bytes
bcdDFUVersion 1.10
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0148
bNumInterfaces 4
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 500mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 3
bFunctionClass 1 Audio
bFunctionSubClass 0
bFunctionProtocol 32
iFunction 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 32
iInterface 3
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 2.00
bCategory 8
wTotalLength 0x00a7
bmControls 0x00
AudioControl Interface Descriptor:
bLength 8
bDescriptorType 36
bDescriptorSubtype 10 (CLOCK_SOURCE)
bClockID 41
bmAttributes 3 Internal programmable clock
bmControls 0x07
Clock Frequency Control (read/write)
Clock Validity Control (read-only)
bAssocTerminal 0
iClockSource 9
AudioControl Interface Descriptor:
bLength 8
bDescriptorType 36
bDescriptorSubtype 11 (CLOCK_SELECTOR)
bClockID 40
bNrInPins 1
baCSourceID(0) 41
bmControls 0x03
Clock Selector Control (read/write)
iClockSelector 8
AudioControl Interface Descriptor:
bLength 17
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 2
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bCSourceID 40
bNrChannels 8
bmChannelConfig 0x00000000
iChannelNames 19
bmControls 0x0000
iTerminal 6
AudioControl Interface Descriptor:
bLength 42
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 10
bSourceID 2
bmaControls(0) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(1) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(2) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(3) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(4) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(5) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(6) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(7) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(8) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
iFeature 0
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 20
wTerminalType 0x0301 Speaker
bAssocTerminal 0
bSourceID 10
bCSourceID 40
bmControls 0x0000
iTerminal 0
AudioControl Interface Descriptor:
bLength 17
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Microphone
bAssocTerminal 0
bCSourceID 40
bNrChannels 8
bmChannelConfig 0x00000000
iChannelNames 19
bmControls 0x0000
iTerminal 0
AudioControl Interface Descriptor:
bLength 42
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 11
bSourceID 1
bmaControls(0) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(1) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(2) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(3) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(4) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(5) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(6) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(7) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
bmaControls(8) 0x0000000f
Mute Control (read/write)
Volume Control (read/write)
iFeature 0
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 22
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 11
bCSourceID 40
bmControls 0x0000
iTerminal 7
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 4
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 2
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 4
AudioStreaming Interface Descriptor:
bLength 16
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bmControls 0x00
bFormatType 1
bmFormats 0x00000001
PCM
bNrChannels 8
bmChannelConfig 0x00000000
iChannelNames 11
AudioStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bSubslotSize 4
bBitResolution 24
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x01 EP 1 OUT
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 1
AudioStreaming Endpoint Descriptor:
bLength 8
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x00
bmControls 0x00
bLockDelayUnits 2 Decoded PCM samples
wLockDelay 0x0008
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 17
Transfer Type Isochronous
Synch Type None
Usage Type Feedback
wMaxPacketSize 0x0004 1x 4 bytes
bInterval 4
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 5
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 32
iInterface 5
AudioStreaming Interface Descriptor:
bLength 16
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 22
bmControls 0x00
bFormatType 1
bmFormats 0x00000001
PCM
bNrChannels 8
bmChannelConfig 0x00000000
iChannelNames 19
AudioStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bSubslotSize 4
bBitResolution 24
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 1
AudioStreaming Endpoint Descriptor:
bLength 8
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x00
bmControls 0x00
bLockDelayUnits 2 Decoded PCM samples
wLockDelay 0x0008
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 254 Application Specific Interface
bInterfaceSubClass 1 Device Firmware Update
bInterfaceProtocol 1
iInterface 10
Device Firmware Upgrade Interface Descriptor:
bLength 9
bDescriptorType 33
bmAttributes 7
Will Not Detach
Manifestation Tolerant
Upload Supported
Download Supported
wDetachTimeout 250 milliseconds
wTransferSize 64 bytes
bcdDFUVersion 1.10
pacmd list-sources inputs：
index: 16
name: <alsa_output.usb-M-Audio_M-Track_Eight-00.analog-surround-71.monitor>
driver: <module-alsa-card.c>
flags: DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
state: RUNNING
suspend cause: (none)
priority: 1040
volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB, rear-left: 65536 / 100% / 0.00 dB, rear-right: 65536 / 100% / 0.00 dB, front-center: 65536 / 100% / 0.00 dB, lfe: 65536 / 100% / 0.00 dB, side-left: 65536 / 100% / 0.00 dB, side-right: 65536 / 100% / 0.00 dB
balance 0.00
base volume: 65536 / 100% / 0.00 dB
volume steps: 65537
muted: no
current latency: 0.00 ms
max rewind: 11 KiB
sample spec: s32le 8ch 44100Hz
channel map: front-left,front-right,rear-left,rear-right,front-center,lfe,side-left,side-right
Surround 7.1
used by: 5
linked by: 5
configured latency: 40.00 ms; range is 8.00 .. 743.04 ms
monitor_of: 7
card: 5 <alsa_card.usb-M-Audio_M-Track_Eight-00>
module: 27
properties:
device.description = "Monitor of M-Track Eight Analog Surround 7.1"
device.class = "monitor"
alsa.card = "2"
alsa.card_name = "M-Track Eight"
alsa.long_card_name = "M-Audio M-Track Eight at usb-0000:00:14.0-5.4, high speed"
alsa.driver_name = "snd_usb_audio"
device.bus_path = "pci-0000:00:14.0-usb-0:5.4:1.0"
sysfs.path = "/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.4/1-5.4:1.0/sound/card2"
udev.id = "usb-M-Audio_M-Track_Eight-00"
device.bus = "usb"
device.vendor.id = "0763"
device.vendor.name = "M-Audio"
device.product.id = "4003"
device.product.name = "M-Track Eight"
device.serial = "M-Audio_M-Track_Eight"
device.string = "2"
module-udev-detect.discovered = "1"
device.icon_name = "audio-card-usb"
这是一段录音：
parecord -r --format=s24le --file-format=wav ./foo.wav
file ./foo.wav
./foo.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 24 bit, stereo 44100 Hz
声音来自麦克风并被剪辑在设备上（显示 vu 计红色条）。
答案1
我没有看到任何明显的东西，但有两个想法：
USB 设备有两种配置，但从显示的信息来看，它们似乎是相同的。所以我不知道它们是做什么用的。您可以尝试切换到另一个（
usb_modeswitch首先卸载内核模块），看看是否会改变任何东西如果我正确读取描述符，您将在 4 个字节中传输 24 位。如果通用 USB 音频驱动程序选择了错误的 3 个字节，则最终可能会得到最高有效字节为零，这会将级别限制为 12.5%（与您观察到的 15% 相匹配）。
您可以通过以
parecord24 位格式录制（例如）到某些文件（WAV 或原始）并使用十六进制编辑器检查来验证这一点。如果所有样本的 MSB 为零，即使您生成的卷在 Mac 或 Windows 上剪辑，也很可能出现这种情况。此外，您可以用来
wireshark捕获 USB 数据包，这样您就可以比较样本中是否有额外的第三个字节，但未将其纳入记录的数据中。
在这种情况下，这是驱动程序中的错误，因此请在 ALSA 内核列表中提交错误报告。
快速浏览用例：通常人们会购买 M-track 8 之类的东西来使用多个麦克风进行录音，例如一个乐队，其中每个成员都有一个或两个麦克风（人声 + 乐器）。在这种情况下，您只需从 Pulseaudio 获取所有 8 个通道（禁用缩混），并且您的 DAW 将选择您实际录制的通道。
通常您甚至会为此完全禁用 Pulseaudio，因为它只会增加延迟，然后直接转到 ALSA，或者使用 Jack 而不是 Pulseaudio。
“我希望我的笔记本电脑能够播放到我的 7.1 环绕扬声器或立体声耳机。然后，如果我进行电话会议，我只希望人们能听到我的声音。
好的，您只有一个麦克风，这就是用例中的全部内容。您还想保留 Pulseaudio，因为您没有延迟问题，并且您主要使用 8 个通道进行输出。
所以看看模块重映射源并做类似的事情
load-module module-remap-source master=alsa_input.usb-MTRACK.analog-stereo channels=1 master_channel_map=front-left channel_map=mono
其中front-left是您的麦克风所在的通道，并MTRACK替换为您的 M-Track 源的实际名称（例如使用pactl list short）。然后从新的源进行记录。
如果唯一的实际问题是 Pulseaudio 将所有 8 个通道缩混为立体声并降低电平，那么您现在应该没问题了。
如果还有其他问题，请按照评论中的描述，在不使用 Pulseaudio 的情况下仅使用 ALSA 测试录制所有 8 个通道，这样我们就可以排除 Pulseaudio 并查看问题是否出在 ALSA 驱动程序中。