Hi, I saw this thread: USB Audio sample rate - #9 by grahamh
I have a similar CM106 USB audio card.
The connection I want is RPi4->USB->CM106->TOSLink->Receiver->Speakers.
The purpose is for routing a large number of audio inputs through the receiver and switching them there. The receiver decodes DD 5.1 and DTS.
If I use “Best” or “Optimal” in the audio settings, everything is working fine on multichannel audio streams that are passed through to the receiver. However, in the OSD menu and on 2-channel sources (e.g. YouTube plugin), I get about 10Hz annoying clicking in the audio output.
If I use “Fixed” with Limit set to 48KHz, there is no clicking. However, by doing so, I lose the Passthrough option. All audio is downmixed to 2-channel PCM so there is nothing for the receiver to decode.
On that sound card I tried selecting the default output, the ‘surround21’ output and the ‘SPD/IF’ output with similar results.
I’m thinking that what I need is to select a fixed sample rate for downmixed output only (since based on my experiments the USB DAC seems only tolerant of 48KHz, despite what it advertises), but still passing through multichannel streams without transcoding/resampling.
The sound card advertises:
2025-06-20 22:39:00.126 T:634 info <general>: CAESinkALSA::EnumerateDevice - device sysdefault:CARD=vc4hdmi0 description vc4-hdmi-0, MAI PCM i2s-hifi-0
Default Audio Device
2025-06-20 22:39:00.127 T:634 info <general>: CAESinkALSA::EnumerateDevice - device hdmi:CARD=vc4hdmi0,DEV=0 description vc4-hdmi-0, MAI PCM i2s-hifi-0
HDMI Audio Output
2025-06-20 22:39:00.137 T:634 info <general>: CAESinkALSA::EnumerateDevice - device sysdefault:CARD=ICUSBAUDIO7D description ICUSBAUDIO7D, USB Audio
Default Audio Device
2025-06-20 22:39:00.154 T:634 info <general>: CAESinkALSA::EnumerateDevice - device @:CARD=ICUSBAUDIO7D,DEV=0 description ICUSBAUDIO7D, USB Audio
Front output / input
2025-06-20 22:39:00.167 T:634 info <general>: CAESinkALSA::EnumerateDevice - device surround21:CARD=ICUSBAUDIO7D,DEV=0 description ICUSBAUDIO7D, USB Audio
2.1 Surround output to Front and Subwoofer speakers
2025-06-20 22:39:00.168 T:634 info <general>: CAESinkALSA::EnumerateDevice - device iec958:CARD=ICUSBAUDIO7D,DEV=0 description ICUSBAUDIO7D, USB Audio
IEC958 (S/PDIF) Digital Audio Output
2025-06-20 22:39:00.169 T:634 info <general>: CAESinkALSA - Unable to open device "sysdefault:CARD=vc4hdmi1" for playback
2025-06-20 22:39:00.170 T:634 info <general>: CAESinkALSA - Unable to open device "hdmi:CARD=vc4hdmi1,DEV=0" for playback
2025-06-20 22:39:00.171 T:634 info <general>: Found 1 Lists of Devices
2025-06-20 22:39:00.171 T:634 info <general>: Enumerated ALSA devices:
2025-06-20 22:39:00.171 T:634 info <general>: Device 1
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceName : sysdefault:CARD=vc4hdmi0
2025-06-20 22:39:00.171 T:634 info <general>: m_displayName : vc4-hdmi-0
2025-06-20 22:39:00.171 T:634 info <general>: m_displayNameExtra: MAI PCM i2s-hifi-0
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceType : AE_DEVTYPE_PCM
2025-06-20 22:39:00.171 T:634 info <general>: m_channels : FL, FR
2025-06-20 22:39:00.171 T:634 info <general>: m_sampleRates : 32000,44100,48000
2025-06-20 22:39:00.171 T:634 info <general>: m_dataFormats : AE_FMT_S24NE3,AE_FMT_S24NE4,AE_FMT_S32NE,AE_FMT_S16NE,AE_FMT_S16LE,AE_FMT_S16BE
2025-06-20 22:39:00.171 T:634 info <general>: m_streamTypes : No passthrough capabilities
2025-06-20 22:39:00.171 T:634 info <general>: Device 2
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceName : hdmi:CARD=vc4hdmi0,DEV=0
2025-06-20 22:39:00.171 T:634 info <general>: m_displayName : vc4-hdmi-0
2025-06-20 22:39:00.171 T:634 info <general>: m_displayNameExtra: SEC EPSON PJ on HDMI
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceType : AE_DEVTYPE_HDMI
2025-06-20 22:39:00.171 T:634 info <general>: m_channels : FL, FR
2025-06-20 22:39:00.171 T:634 info <general>: m_sampleRates : 32000,44100,48000
2025-06-20 22:39:00.171 T:634 info <general>: m_dataFormats : AE_FMT_RAW,AE_FMT_S24NE3,AE_FMT_S24NE4,AE_FMT_S32NE,AE_FMT_S16NE,AE_FMT_S16LE,AE_FMT_S16BE,AE_FMT_U8,AE_FMT_RAW
2025-06-20 22:39:00.171 T:634 info <general>: m_streamTypes : STREAM_TYPE_AC3,STREAM_TYPE_DTSHD,STREAM_TYPE_DTSHD_MA,STREAM_TYPE_DTSHD_CORE,STREAM_TYPE_DTS_1024,STREAM_TYPE_DTS_2048,STREAM_TYPE_DTS_512,STREAM_TYPE_EAC3,STREAM_TYPE_TRUEHD
2025-06-20 22:39:00.171 T:634 info <general>: Device 3
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceName : @:CARD=ICUSBAUDIO7D,DEV=0
2025-06-20 22:39:00.171 T:634 info <general>: m_displayName : ICUSBAUDIO7D (@:CARD=ICUSBAUDIO7D,DEV=0)
2025-06-20 22:39:00.171 T:634 info <general>: m_displayNameExtra: Analog
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceType : AE_DEVTYPE_PCM
2025-06-20 22:39:00.171 T:634 info <general>: m_channels : FL, FR, FC, LFE, SL, SR, BL, BR
2025-06-20 22:39:00.171 T:634 info <general>: m_sampleRates : 48000
2025-06-20 22:39:00.171 T:634 info <general>: m_dataFormats : AE_FMT_S16NE,AE_FMT_S16LE
2025-06-20 22:39:00.171 T:634 info <general>: m_streamTypes : No passthrough capabilities
2025-06-20 22:39:00.171 T:634 info <general>: Device 4
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceName : surround21:CARD=ICUSBAUDIO7D,DEV=0
2025-06-20 22:39:00.171 T:634 info <general>: m_displayName : ICUSBAUDIO7D (surround21:CARD=ICUSBAUDIO7D,DEV=0)
2025-06-20 22:39:00.171 T:634 info <general>: m_displayNameExtra: Analog
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceType : AE_DEVTYPE_PCM
2025-06-20 22:39:00.171 T:634 info <general>: m_channels : FL, FR, BL, BR, FC, LFE, SL, SR, UNKNOWN1, UNKNOWN2, UNKNOWN3, UNKNOWN4, UNKNOWN5, UNKNOWN6, UNKNOWN7, UNKNOWN8
2025-06-20 22:39:00.171 T:634 info <general>: m_sampleRates : 44100,48000
2025-06-20 22:39:00.171 T:634 info <general>: m_dataFormats : AE_FMT_S16NE,AE_FMT_S16LE
2025-06-20 22:39:00.171 T:634 info <general>: m_streamTypes : No passthrough capabilities
2025-06-20 22:39:00.171 T:634 info <general>: Device 5
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceName : iec958:CARD=ICUSBAUDIO7D,DEV=0
2025-06-20 22:39:00.171 T:634 info <general>: m_displayName : ICUSBAUDIO7D
2025-06-20 22:39:00.171 T:634 info <general>: m_displayNameExtra: S/PDIF
2025-06-20 22:39:00.171 T:634 info <general>: m_deviceType : AE_DEVTYPE_IEC958
2025-06-20 22:39:00.171 T:634 info <general>: m_channels : FL, FR, FC, LFE, SL, SR, BL, BR
2025-06-20 22:39:00.171 T:634 info <general>: m_sampleRates : 44100,48000,96000
2025-06-20 22:39:00.171 T:634 info <general>: m_dataFormats : AE_FMT_RAW,AE_FMT_S16NE,AE_FMT_S16LE
2025-06-20 22:39:00.171 T:634 info <general>: m_streamTypes : STREAM_TYPE_AC3,STREAM_TYPE_DTSHD_CORE,STREAM_TYPE_DTS_1024,STREAM_TYPE_DTS_2048,STREAM_TYPE_DTS_512
2025-06-20 22:39:00.172 T:634 warning <general>: ValidateOutputDevices: audio output device setting has been updated from 'ALSA:@:CARD=ICUSBAUDIO7D,DEV=0|ICUSBAUDIO7D (@:CARD=ICUSBAUDIO7D,DEV=0) (ICUSBAUDIO7D)' to 'ALSA:@:CARD=ICUSBAUDIO7D,DEV=0|ICUSBAUDIO7D (@:CARD=ICUSBAUDIO7D,DEV=0)'
2025-06-20 22:39:00.180 T:635 info <general>: CActiveAESink::OpenSink - initialize sink
2025-06-20 22:39:00.180 T:635 info <general>: CAESinkALSA::Initialize - Attempting to open device "@:CARD=ICUSBAUDIO7D,DEV=0"
2025-06-20 22:39:00.187 T:635 info <general>: CAESinkALSA::Initialize - Opened device "surround40:CARD=ICUSBAUDIO7D,DEV=0"
2025-06-20 22:39:00.187 T:635 info <general>: CAESinkALSA::InitializeHW - Your hardware does not support AE_FMT_FLOAT, trying other formats
2025-06-20 22:39:00.187 T:635 info <general>: CAESinkALSA::InitializeHW - Using data format AE_FMT_S16NE