This 7.1 analog sound card identifies as the following: 0d8c:0102 C-Media Electronics, Inc. CM106 Like Sound Device (lsusb)
1 [ICUSBAUDIO7D ]: USB-Audio - ICUSBAUDIO7D (/proc/asound/cards)
It has the following four-channel analog stream layout:
Interface 1
Altset 3
Format: S16_LE
Channels: 4
Endpoint: 6 OUT (ADAPTIVE)
Rates: 44100, 48000
Bits: 16
Channel map: FL FR FC LFE
(/proc/asound/card1/stream0)
This layout makes it impossible to play audio to the surround (SL/SR) speakers plugged into the "Surround" jack in 4 channel mode. Instead, set six_channel so that the six-channel layout will be used to access those speakers:
Interface 1
Altset 4
Format: S16_LE
Channels: 6
Endpoint: 6 OUT (ADAPTIVE)
Rates: 44100, 48000
Bits: 16
Channel map: FL FR FC LFE SL SR
Tested with speaker-test -Dsurround40:CARD=ICUSBAUDIO7D,DEV=0 -c4
The speaker system that required surround40 in order to downmix LFE into the front/rear mix is a Klipsch ProMedia v.2-400, which has 4 speakers and a subwoofer with an internal crossover, connected via front and rear stereo analog cables.
This 7.1 analog sound card identifies as the following: 0d8c:0102 C-Media Electronics, Inc. CM106 Like Sound Device (lsusb) 1 [ICUSBAUDIO7D ]: USB-Audio - ICUSBAUDIO7D (/proc/asound/cards)
It has the following four-channel analog stream layout: Interface 1 Altset 3 Format: S16_LE Channels: 4 Endpoint: 6 OUT (ADAPTIVE) Rates: 44100, 48000 Bits: 16 Channel map: FL FR FC LFE (/proc/asound/card1/stream0)
This layout makes it impossible to play audio to the surround (SL/SR) speakers plugged into the "Surround" jack in 4 channel mode. Instead, set six_channel so that the six-channel layout will be used to access those speakers: Interface 1 Altset 4 Format: S16_LE Channels: 6 Endpoint: 6 OUT (ADAPTIVE) Rates: 44100, 48000 Bits: 16 Channel map: FL FR FC LFE SL SR
Tested with speaker-test -Dsurround40:CARD=ICUSBAUDIO7D,DEV=0 -c4
The speaker system that required surround40 in order to downmix LFE into the front/rear mix is a Klipsch ProMedia v.2-400, which has 4 speakers and a subwoofer with an internal crossover, connected via front and rear stereo analog cables.