Ubuntu – No sound from right speakers

X-Fis (even the USB ones) work. They didn't used to but ALSA added drivers for them over a year ago and most people now don't seem to have an issue with them. I know the first review of one on Newegg complains about Linux support but seriously, there used to be threads complaining about them every day, that's fizzled off into nothing.

You'll find with most of the better consumer audio devices that a lot of the special hardware (read: CMSS-3D, EAX, etc) requires special Windows-only software. You'll be able to hear sound and you'll be able to hear it in 5.1 setups with DTS (if that applies) but you won't get some of the fancier effects.

Alternatively, you can use something as simple as a HDMI connection (if your Mini-ATX board has one, or through a graphics card) and port that into an AV receiver. Lots more money but much better sound and equaliser options (IMO).

First, you should define in ALSA that you have 6 channels. You can refer to this post. Basically, you launch alsamixer and you define (for the right soundcard) the number of channels to 6. Then you store the configuration in order to be reloaded on reboot:

sudo alsactl store

Then pulseaudio should be configure (pulse is the sound layer that will be used by apps and talks directly to ALSA.). You should define the number of channels in /etc/pulse/daemon.conf, like said in this documentation:

default-sample-channels = 6

Also, to enable the remixing of low frequencies in your subwoofer, you should activate this in your sound card by editing the same file /etc/pulse/daemon.conf:

enable-lfe-remixing = yes

Then, you maybe need to reboot, or kill and relaunch pulseaudio:

pulseaudio -k
pulseaudio -D

Then, pavucontrol may help you, as replied in this question. In the configuration tab, you should see different profiles for your sound card, for example "Suround analogiq 4.1" that means that you want to use 4 channels and 1 subwoofer.