Sennheiser GSX 1000/1200 on Linux

sennheiser.md

UPDATE: this is out of date and although it worked for me at the time, there is a better solution to make it work: https://github.com/evilphish/sennheiser-gsx-1000

In order to make the Sennheiser amplifier GSX 1000/1200 work on Linux as a 7.1 device it is needed to change a configuration file of pulseaudio. Execute this command to identify the output sound cards:

aplay -l

This is a sample output

card 1: Audio [GSX 1000 Main Audio], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: Audio [GSX 1000 Main Audio], device 1: USB Audio [USB Audio #1]
Subdevices: 0/1
Subdevice #0: subdevice #0

To identify the input sound cards:

arecord -l

This is a sample outuput

card 1: Audio [GSX 1000 Main Audio], device 0: USB Audio [USB Audio]
Subdevices: 0/1
Subdevice #0: subdevice #0

For the playback, subdevice 1/1 is the 7.1 playback device ("Speakers" equivalent on Windows) and the subdevice 0/1 should be the "Headset earphone". Edit /etc/pulse/default.pa, uncomment the lines below and set the correct device:

load-module module-alsa-source device=hw:1,0    # capture device, card 1, subdevice 0
load-module module-alsa-sink device=hw:1,1 channels=8    # playback device, card 1, subdevice 1, 7.1 channels

Information taken from here

The GSX1200 plays on the head phones, but when I click the switch between headphones and speakers the audio drops out completely.
If I turn the volume dial the volume only goes down. Running kubuntu 19.10 with a GSX 1200 as well. Not sure how to translate the aplay -l output to the stanza /etc/pulse/default.pa.
The sections related to the GSX 1200 are:
Output:
card 1: Audio [GSX 1200 Pro Main Audio], device 0: USB Audio [USB Audio]
Subdevices: 0/1
Subdevice #0: subdevice #0
card 1: Audio [GSX 1200 Pro Main Audio], device 1: USB Audio [USB Audio #1]
Subdevices: 1/1
Subdevice #0: subdevice #0
Input:
card 1: Audio [GSX 1200 Pro Main Audio], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0

What is currently in my file:
load-module module-alsa-source device=hw:1,0 # capture device, card 1, subdevice 0
load-module module-alsa-sink device=hw:1,1 channels=8 # playback device, card 1, subdevice 1, 7.1 channels

@evilphish Mate, your solution is the only one that worked! Thanks for posting that. Ran your shell script, installed pavucontrol and everything works now. The only thing I needed to do even after following your instructions was to set my GSX 1000 Main Audio main output as the fallback device by clicking on the green check next to it in Pulseaudio Volume Control because otherwise it was still redirecting all the sound to my headphones (the chat output).

Edit:
Note to future self - I didn't keep any of the lines described in this original gist, they didn't work no matter what I did.

@evilphish, thank you very much. Your solution is working for me. Very happy you did this!!