I have a Technics SL-1210 next to my PC and wanted to use my Native Instruments Komplete Audio 6 MK2’s back side inputs 3 and 4 (stereo) to listen to vinyls while i’m working (“pass-through” or “loopback”) on my Manjaro Linux machine using pulseaudio.

the first problem: Only Inputs 1/2 are available in pulse audios pavucontrol in the tab “configuration” where you can set profiles for your card. to view sinks (outputs) using the shell you could also use pacmd list-sinks.

so it seems the there is no configuration fo my usecase “Input 3/4 -> Output 1/2”… Lets change that:

open /usr/share/pulseaudio/alsa-mixer/profile-sets/native-instruments-komplete-audio6.conf (at least on my manjaro machine it’s located there) and add our desired configuration:

[Profile output:analog-stereo-out-ab+input:analog-stereo-in-cd]
description = Analog Stereo Output 1/2, Analog Stereo Input 3/4
output-mappings = analog-stereo-out-ab
input-mappings = analog-stereo-in-cd
priority = 80
skip-probe = yes

i’ve used a profile and just changed the description and the input-mappings (from ab to cd).

now after a pulseaudio restart using pulseaudio -k i have “Input 3/4” available and “Output 1/2” when selecting the new profile in pavucontrol.

last thing to do is to “loopback” the input “3/4” directly to our output “1/2”, this is done using the following command:
pactl load-module module-loopback source=alsa_input.usb-Native_Instruments_Komplete_Audio_6_MK2_247C57F8-00.analog-stereo-in-cd sink=alsa_output.usb-Native_Instruments_Komplete_Audio_6_MK2_247C57F8-00.analog-stereo-out-ab
note: your device names might differ from mine, you can find your names using the following commands:

list sources (inputs):
pacmd list-sources | grep -E 'name:|index:'

list sinks (outputs):
pacmd list-sinks | grep -E 'name:|index:'

now you should hear the input from “Input 3/4” on your speakers connected to “Output 1/2”! :)

if you want your changes persistent you can either just copy the above command without pactl to /etc/pulse/default.pa or you can created a custom default.pa in your home directory:

open or create ~/.config/pulse/default.pa and put the following in:

.include /etc/pulse/default.pa

load-module module-loopback source=alsa_input.usb-Native_Instruments_Komplete_Audio_6_MK2_247C57F8-00.analog-stereo-in-cd sink=alsa_output.usb-Native_Instruments_Komplete_Audio_6_MK2_247C57F8-00.analog-stereo-out-ab

note that if you changed your commandline earlier you have to make this changes here too, obviously