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"

use the two outputs at the same time

what do you mean? use voice channel and game channel simultaneously?
I'm afraid it'll exceed physical bandwidth capacity of the base station transmitter.
thus sound will be always crackled, indeed.

I got it working by switching the base station from a USB 2.0 to a USB 3.0. Now I can use the Voice and Game channel simultaneously!