Astro A50 support on Linux - basic configuration for PulseAudio 13 (tested on Ubuntu's 13.99.1). Install the files and reboot, to make sure udev and PA reloaded :-)

PA profile-set astro-a50-gen4.conf

; /usr/share/pulseaudio/alsa-mixer/profile-sets/astro-a50-gen4.conf

[General]
auto-profiles = yes

[Mapping analog-voice]
description = Voice
device-strings = hw:%f,0,0
channel-map = left,right
paths-output = steelseries-arctis-output-chat-common
intended-roles = phone

[Mapping analog-voice-input]
description = Voice
device-strings = hw:%f,0,0
channel-map = mono
paths-input = usb-gaming-headset-input
intended-roles = phone

[Mapping analog-game]
description = Game
device-strings = hw:%f,1,0
channel-map = left,right
paths-output = steelseries-arctis-output-game-common
direction = output

[Profile output:analog-voice+output:analog-game+input:analog-voice]
output-mappings = analog-voice analog-game
input-mappings = analog-voice-input
priority = 5100
skip-probe = yes

udev 90-astro-50.rules

# /etc/udev/rules.d/90-astro-50.rules

# ID 9886:002c is for Astro A50 Gen4
ACTION=="change", SUBSYSTEMS=="usb", ATTRS{idVendor}=="9886", ATTRS{idProduct}=="002c", ENV{PULSE_PROFILE_SET}="astro-a50-gen4.conf"