Can you check with: amixer | grep -A 6 Loopback
Simple mixer control 'Left Digital Loopback',0 Capabilities: volume volume-joined penum Playback channels: Mono Capture channels: Mono Limits: 0 - 7 Mono: 0 [0%] [-99999.99dB] Simple mixer control 'Left1 Analog Loopback',0 Capabilities: pswitch pswitch-joined penum Playback channels: Mono Mono: Playback [off] Simple mixer control 'Left2 Analog Loopback',0 Capabilities: pswitch pswitch-joined penum Playback channels: Mono Mono: Playback [off] Simple mixer control 'PreDriv',0 Capabilities: pvolume penum Playback channels: Front Left - Front Right -- Simple mixer control 'Right Digital Loopback',0 Capabilities: volume volume-joined penum Playback channels: Mono Capture channels: Mono Limits: 0 - 7 Mono: 0 [0%] [-99999.99dB] Simple mixer control 'Right1 Analog Loopback',0 Capabilities: pswitch pswitch-joined penum Playback channels: Mono Mono: Playback [off] Simple mixer control 'Right2 Analog Loopback',0 Capabilities: pswitch pswitch-joined penum Playback channels: Mono Mono: Playback [off] Simple mixer control 'TX1',0 Capabilities: cenum Items: 'Analog' 'Digimic0' -- Simple mixer control 'Voice Analog Loopback',0 Capabilities: pswitch pswitch-joined penum Playback channels: Mono Mono: Playback [off] Simple mixer control 'Voice Digital Loopback',0 Capabilities: volume volume-joined penum Playback channels: Mono Capture channels: Mono Limits: 0 - 41 Mono: 0 [0%] [-99999.99dB]