pulseaudio monitor device:
Source #0
        State: SUSPENDED
        Name: alsa_output.pci-0000_00_1b.0.analog-surround-71.monitor
        Description: Monitor of Internes Audio Analog Surround 7.1
        Driver: module-alsa-card.c
        Sample Specification: s16le 8ch 44100Hz
        Channel Map: front-left,front-right,rear-left,rear-right,front-center,lfe,side-left,side-right
        Owner Module: 6
ffmpeg not working:
ffmpeg -hide_banner -y -ac 8 -f pulse -ar 44100 -i alsa_output.pci-0000_00_1b.0.analog-surround-71.monitor -codec:a libvorbis -qscale:a 8 -f ogg /home/Shared/pulse-record.ogg
alsa_output.pci-0000_00_1b.0.analog-surround-71.monitor: No such process

ffmpeg working:
ffmpeg -hide_banner -y -ac 6 -f pulse -ar 44100 -i alsa_output.pci-0000_00_1b.0.analog-surround-71.monitor -codec:a libvorbis -qscale:a 8 -f ogg /home/Shared/pulse-record.ogg