~/.asoundrc (2 channels)

# ~/.asoundrc
# ===========

# 1. 8 microphones to one device
#   (only 2 channels of 8 are used right now)
# -------------------------------------------

pcm.8mics_multi {
    type multi
    slaves {
        a { pcm "hw:2,0" channels 1 }
        b { pcm "hw:3,0" channels 1 }
#        c { pcm "hw:4,0" channels 1 }
#        d { pcm "hw:5,0" channels 1 }
#        e { pcm "hw:6,0" channels 1 }
#        f { pcm "hw:7,0" channels 1 }
#        g { pcm "hw:8,0" channels 1 }
#        h { pcm "hw:9,0" channels 1 }
    }
    bindings [
        { slave a channel 0 }
        { slave b channel 0 }
#        { slave c channel 0 }
#        { slave d channel 0 }
#        { slave e channel 0 }
#        { slave f channel 0 }
#        { slave g channel 0 }
#        { slave h channel 0 }
    ]
}

pcm.8mics {
    type plug
    slave { pcm "8mics_multi" channels 2 }        # channels 8 -> channels 2
    hint { show on description "8 mics" }
}

# 2. Each microphone to a separate device
# ---------------------------------------

pcm.mic1 { type plug slave { pcm "hw:2,0" channels 1 } hint { show on description "Mic 1" } }
pcm.mic2 { type plug slave { pcm "hw:3,0" channels 1 } hint { show on description "Mic 2" } }
pcm.mic3 { type plug slave { pcm "hw:4,0" channels 1 } hint { show on description "Mic 3" } }
pcm.mic4 { type plug slave { pcm "hw:5,0" channels 1 } hint { show on description "Mic 4" } }
pcm.mic5 { type plug slave { pcm "hw:6,0" channels 1 } hint { show on description "Mic 5" } }
pcm.mic6 { type plug slave { pcm "hw:7,0" channels 1 } hint { show on description "Mic 6" } }
pcm.mic7 { type plug slave { pcm "hw:8,0" channels 1 } hint { show on description "Mic 7" } }
pcm.mic8 { type plug slave { pcm "hw:9,0" channels 1 } hint { show on description "Mic 8" } }