USB DAC 8 Channels - 2 Channels Available ONLY

[redger]

Help,
I have a Creative X3 7.1 channel USB DAC which works perefectly in Ubuntu / Kodi and Librelec x86 … but is only partly functional in CoreElec

For some reason only 2 channels (of the 8 in hardware) are recognised in CoreElec and I have no idea why or how to debug

cat /proc/asound/X3/stream0 shows

Creative Technology Ltd Sound Blaster X3 at usb-xhci-hcd.0.auto-1.2, high speed : USB Audio

Playback:
Status: Stop
Interface 4
Altset 1
Format: S16_LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Interface 4
Altset 2
Format: S24_3LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 48000
Data packet interval: 125 us
Interface 4
Altset 3
Format: S32_LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 48000
Data packet interval: 125 us

Capture:
Status: Stop
Interface 5
Altset 1
Format: S16_LE
Channels: 2
Endpoint: 1 IN (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 500 us
Interface 5
Altset 2
Format: S24_3LE
Channels: 2
Endpoint: 1 IN (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 500 us

On x86 the same command shows

Creative Technology Ltd Sound Blaster X3 at usb-0000:00:14.0-3, high speed : USB Audio

Playback:
Status: Stop
Interface 4
Altset 1
Format: S16_LE
Channels: 2
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 16
Channel map: FL FR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 1
Implicit Feedback Mode: No
Interface 4
Altset 2
Format: S16_LE
Channels: 6
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 16
Channel map: FL FR FC LFE RL RR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 2
Implicit Feedback Mode: No
Interface 4
Altset 3
Format: S16_LE
Channels: 8
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 16
Channel map: FL FR FC LFE RL RR SL SR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 3
Implicit Feedback Mode: No
Interface 4
Altset 4
Format: S24_3LE
Channels: 2
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 24
Channel map: FL FR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 4
Implicit Feedback Mode: No
Interface 4
Altset 5
Format: S24_3LE
Channels: 6
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 24
Channel map: FL FR FC LFE RL RR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 5
Implicit Feedback Mode: No
Interface 4
Altset 6
Format: S24_3LE
Channels: 8
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 24
Channel map: FL FR FC LFE RL RR SL SR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 6
Implicit Feedback Mode: No
Interface 4
Altset 7
Format: S32_LE
Channels: 2
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 32
Channel map: FL FR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 7
Implicit Feedback Mode: No
Interface 4
Altset 8
Format: S32_LE
Channels: 6
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 32
Channel map: FL FR FC LFE RL RR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 8
Implicit Feedback Mode: No
Interface 4
Altset 9
Format: S32_LE
Channels: 8
Endpoint: 0x01 (1 OUT) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 125 us
Bits: 32
Channel map: FL FR FC LFE RL RR SL SR
Sync Endpoint: 0x83 (3 IN)
Sync EP Interface: 4
Sync EP Altset: 9
Implicit Feedback Mode: No

Capture:
Status: Stop
Interface 5
Altset 1
Format: S16_LE
Channels: 2
Endpoint: 0x81 (1 IN) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 500 us
Bits: 16
Channel map: FL FR
Interface 5
Altset 2
Format: S24_3LE
Channels: 2
Endpoint: 0x81 (1 IN) (ASYNC)
Rates: 48000, 96000, 192000
Data packet interval: 500 us
Bits: 24
Channel map: FL FR

I went to use the standard log paste for debugging but the webite appears to be non-functional so not attached here but am happy to attach one if you have a preferred location / facility

Is this a known problem ? Is there a known workaround ?

thanks for help & advice