Comment 2 for bug 1516361

it is a bug of alsa driver which allow you to add four speakers when your alc668 are 6 channel codecs

Default sink name: alsa_output.pci-0000_00_1b.0.analog-surround-71
Default source name: alsa_input.pci-0000_00_1b.0.analog-stereo

sys/class/sound/hwC1D0/init_pin_configs:
0x12 0x90a60130
0x14 0x90170110
0x15 0x04211020
0x16 0x40000000
0x18 0x411111f0
0x19 0x411111f0
0x1a 0x411111f0
0x1b 0x411111f0
0x1d 0x40c6832d
0x1e 0x411111f0
0x1f 0x411111f0

/sys/class/sound/hwC1D0/driver_pin_configs:

/sys/class/sound/hwC1D0/user_pin_configs:
0x12 0x90a60130
0x14 0x90170110
0x15 0x04211020
0x16 0x90170152
0x18 0x90170151
0x19 0x90170151
0x1a 0x90170151
0x1b 0x411111f0
0x1d 0x40c6832d
0x1e 0x411111f0
0x1f 0x411111f0